From eb544ea0880a5a9d92634875cbce1341de3342e2 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 09:03:28 -0500
Subject: [PATCH 01/11] Allow `channel_count=2`

---
 shared-bindings/usb_audio/__init__.c            | 2 +-
 shared-module/usb_audio/usb_audio_descriptors.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 49eaa9716f2..7ac882e982b 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -93,7 +93,7 @@
 //|     This function may only be used from ``boot.py``.
 //|
 //|     :param int sample_rate: Samples per second of the streamed audio.
-//|     :param int channel_count: Number of channels. Only mono (1) is supported initially.
+//|     :param int channel_count: Number of channels. Either mono (1) or stereo (2) is supported.
 //|     :param int bits_per_sample: Bits per signed PCM sample. Only 16 is supported initially.
 //|     :param bool microphone: Present a microphone (audio flows board -> host). Enabled by default.
 //|     :param bool speaker: Present a speaker (audio flows host -> board).
diff --git a/shared-module/usb_audio/usb_audio_descriptors.h b/shared-module/usb_audio/usb_audio_descriptors.h
index 1313e198959..8b297c3218f 100644
--- a/shared-module/usb_audio/usb_audio_descriptors.h
+++ b/shared-module/usb_audio/usb_audio_descriptors.h
@@ -30,7 +30,7 @@ size_t usb_audio_descriptor_length(void);
 
 // 16-bit signed LE PCM, mono.
 #define USB_AUDIO_N_BYTES_PER_SAMPLE (2)
-#define USB_AUDIO_N_CHANNELS (1)
+#define USB_AUDIO_N_CHANNELS (2)
 #define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_N_BYTES_PER_SAMPLE * 8)
 
 // Endpoint number for the single isochronous audio data endpoint. Most device

From 2285442c5901a3e91b5445c11d3ec655d34e159f Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 09:09:51 -0500
Subject: [PATCH 02/11] Add error to disallow stereo microphone and speaker

---
 shared-bindings/usb_audio/__init__.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 7ac882e982b..108c8ee2bdf 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -124,6 +124,10 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
         mp_raise_ValueError(MP_ERROR_TEXT("At least one of microphone and speaker must be enabled"));
     }
 
+    if (microphone && speaker && channel_count == 2) {
+        mp_raise_ValueError(MP_ERROR_TEXT("Only mono operation is supported when microphone and speaker are both enabled"));
+    }
+
     if (!shared_module_usb_audio_enable(sample_rate, channel_count, bits_per_sample, microphone, speaker)) {
         mp_raise_RuntimeError(MP_ERROR_TEXT("Cannot change USB devices now"));
     }

From 478762cd1d0338f3d885595f70f1d7d71436db74 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 16:46:31 -0500
Subject: [PATCH 03/11] Support stereo audio device descriptors

---
 shared-bindings/usb_audio/__init__.c          |  16 +-
 shared-module/usb_audio/USBMicrophone.c       |   4 +-
 shared-module/usb_audio/USBSpeaker.c          |  52 ++--
 shared-module/usb_audio/USBSpeaker.h          |  20 +-
 shared-module/usb_audio/__init__.c            | 281 ++++++++++++++----
 .../usb_audio/usb_audio_descriptors.h         |  64 +++-
 supervisor/shared/usb/tusb_config.h           |   8 +-
 7 files changed, 330 insertions(+), 115 deletions(-)

diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 108c8ee2bdf..77c3201fcb5 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -19,9 +19,9 @@
 //| Audio Class (UAC2) microphone: the board is the audio *source* and streams
 //| samples to the host over a USB isochronous IN endpoint.
 //|
-//| This mode requires 1 IN endpoint and 2 interfaces. Generally, microcontrollers
-//| have a limit on the number of endpoints. If you exceed the number of endpoints,
-//| CircuitPython will automatically enter Safe Mode. Even in this case, you may be
+//| This mode requires 1 (mono) or 2 (stereo / bidirectional) IN endpoint and 2 interfaces.
+//| Generally, microcontrollers have a limit on the number of endpoints. If you exceed the number
+//| of endpoints, CircuitPython will automatically enter Safe Mode. Even in this case, you may be
 //| able to enable USB audio by also disabling other USB functions, such as
 //| `usb_hid` or `usb_midi`.
 //|
@@ -61,9 +61,11 @@
 //|         pass
 //|     mic.stop()
 //|
-//| The ``sample_rate`` and ``channel_count`` of the sample played must match the
-//| values passed to `enable`, and the sample must be 16-bit signed; otherwise
-//| ``play`` raises a ``ValueError``.
+//| The ``sample_rate`` and ``channel_count`` of the sample played must match the values passed to `enable`,
+//| and the sample must be 16-bit signed; otherwise ``play`` raises a ``ValueError``.
+//|
+//| If both speaker and headphone features are enabled (bidirectional), only mono operation is
+//| permitted.
 //|
 //| This interface is experimental and may change without notice even in stable
 //| versions of CircuitPython."""
@@ -115,7 +117,7 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     mp_int_t sample_rate = mp_arg_validate_int_range(args[ARG_sample_rate].u_int, 1, USB_AUDIO_MAX_SAMPLE_RATE, MP_QSTR_sample_rate);
-    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_N_CHANNELS, MP_QSTR_channel_count);
+    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_MAX_CHANNELS, MP_QSTR_channel_count);
     mp_int_t bits_per_sample = mp_arg_validate_int(args[ARG_bits_per_sample].u_int, USB_AUDIO_BITS_PER_SAMPLE, MP_QSTR_bits_per_sample);
     bool microphone = args[ARG_microphone].u_bool;
     bool speaker = args[ARG_speaker].u_bool;
diff --git a/shared-module/usb_audio/USBMicrophone.c b/shared-module/usb_audio/USBMicrophone.c
index fd5309abeb9..c9245b2edb2 100644
--- a/shared-module/usb_audio/USBMicrophone.c
+++ b/shared-module/usb_audio/USBMicrophone.c
@@ -107,9 +107,9 @@ size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
         return 0;
     }
 
-    // The negotiated USB format is 16-bit signed mono PCM. For this step the
+    // The negotiated USB format is 16-bit signed PCM. For this step the
     // bound sample is assumed to already be in that format (e.g. a 16-bit signed
-    // mono audiocore.RawSample), so its bytes are copied straight through.
+    // audiocore.RawSample), so its bytes are copied straight through.
     size_t filled = 0;
     while (filled < max_bytes) {
         if (self->buffer_length == 0) {
diff --git a/shared-module/usb_audio/USBSpeaker.c b/shared-module/usb_audio/USBSpeaker.c
index 12921430bc3..63c75dbf5b5 100644
--- a/shared-module/usb_audio/USBSpeaker.c
+++ b/shared-module/usb_audio/USBSpeaker.c
@@ -15,11 +15,6 @@
 
 #include "tusb.h"
 
-// The ring is sized independently of the TinyUSB headers (see USBSpeaker.h);
-// check it still matches the OUT endpoint's software FIFO so the push side can be
-// reasoned about against the USB plumbing.
-MP_STATIC_ASSERT(USB_AUDIO_SPEAKER_RING_SIZE == CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ);
-
 // Only one speaker can be fed by the single USB OUT endpoint at a time. This
 // points at the most recently constructed USBSpeaker, or NULL when none exists,
 // mirroring active_microphone in USBMicrophone.c. The USB background task pushes
@@ -36,7 +31,30 @@ void common_hal_usb_audio_usbspeaker_construct(usb_audio_usbspeaker_obj_t *self)
     self->base.channel_count = usb_audio_channel_count;
     self->base.samples_signed = true;
     self->base.single_buffer = false;
-    self->base.max_buffer_length = USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE;
+    
+    // Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
+    // audiocore.RawSample's convention where base.max_buffer_length is the whole
+    // buffer and get_buffer() returns half of it.
+    self->base.max_buffer_length = (2 * USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER * USB_AUDIO_N_BYTES_PER_SAMPLE * usb_audio_channel_count);
+    self->output_buffer = m_malloc_without_collect(self->base.max_buffer_length);
+    if (self->output_buffer == NULL) {
+        common_hal_usb_audio_usbspeaker_deinit(self);
+        m_malloc_fail(self->base.max_buffer_length);
+    }
+    memset(self->output_buffer, 0, self->base.max_buffer_length);
+
+    // The ring is sized independently of the TinyUSB headers; check it still
+    // matches the OUT endpoint's software FIFO so the push side can be reasoned
+    // about against the USB plumbing.
+    self->ring_len = 16 * ((usb_audio_sample_rate / 1000 + 1) * (USB_AUDIO_N_BYTES_PER_SAMPLE * usb_audio_channel_count));
+    assert(self->ring_len == CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ);
+
+    self->ring = m_malloc_without_collect(self->ring_len);
+    if (self->ring == NULL) {
+        common_hal_usb_audio_usbspeaker_deinit(self);
+        m_malloc_fail(self->ring_len);
+    }
+    memset(self->ring, 0, self->ring_len);
 
     self->ring_head = 0;
     self->ring_tail = 0;
@@ -104,32 +122,32 @@ void usb_audio_usbspeaker_background_drain(const uint8_t *in, size_t n) {
     if (self == NULL || n == 0) {
         return;
     }
-    if (n >= USB_AUDIO_SPEAKER_RING_SIZE) {
+    if (n >= self->ring_len) {
         // A single chunk larger than the whole ring can only contribute its
         // newest tail. (Cannot happen with USB packets << ring size, but keep
         // the copies provably in-bounds.)
-        in += n - USB_AUDIO_SPEAKER_RING_SIZE;
-        n = USB_AUDIO_SPEAKER_RING_SIZE;
+        in += n - self->ring_len;
+        n = self->ring_len;
     }
 
     common_hal_mcu_disable_interrupts();
 
-    size_t free_space = USB_AUDIO_SPEAKER_RING_SIZE - self->ring_count;
+    size_t free_space = self->ring_len - self->ring_count;
     if (n > free_space) {
         // Overrun: advance the read cursor past the oldest bytes we're about to
         // overwrite, keeping latency bounded and following the newest host audio.
         size_t drop = n - free_space;
-        self->ring_tail = (self->ring_tail + drop) % USB_AUDIO_SPEAKER_RING_SIZE;
+        self->ring_tail = (self->ring_tail + drop) % self->ring_len;
         self->ring_count -= drop;
     }
 
     // Copy in one or two segments, wrapping at the end of the ring.
-    size_t first = MIN(n, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_head);
+    size_t first = MIN(n, self->ring_len - self->ring_head);
     memcpy(&self->ring[self->ring_head], in, first);
     if (n > first) {
         memcpy(&self->ring[0], in + first, n - first);
     }
-    self->ring_head = (self->ring_head + n) % USB_AUDIO_SPEAKER_RING_SIZE;
+    self->ring_head = (self->ring_head + n) % self->ring_len;
     self->ring_count += n;
 
     common_hal_mcu_enable_interrupts();
@@ -157,12 +175,12 @@ uint32_t common_hal_usb_audio_usbspeaker_read(usb_audio_usbspeaker_obj_t *self,
     // but stay defensive so the returned count is always a whole number).
     to_copy -= to_copy % bytes_per_frame;
 
-    size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
+    size_t first = MIN(to_copy, self->ring_len - self->ring_tail);
     memcpy(buffer, &self->ring[self->ring_tail], first);
     if (to_copy > first) {
         memcpy((uint8_t *)buffer + first, &self->ring[0], to_copy - first);
     }
-    self->ring_tail = (self->ring_tail + to_copy) % USB_AUDIO_SPEAKER_RING_SIZE;
+    self->ring_tail = (self->ring_tail + to_copy) % self->ring_len;
     self->ring_count -= to_copy;
     common_hal_mcu_enable_interrupts();
 
@@ -199,12 +217,12 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
     // It is never preempted by the producer, so no interrupt guard is required.
     size_t to_copy = MIN(self->ring_count, (size_t)half);
 
-    size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
+    size_t first = MIN(to_copy, self->ring_len - self->ring_tail);
     memcpy(out, &self->ring[self->ring_tail], first);
     if (to_copy > first) {
         memcpy(out + first, &self->ring[0], to_copy - first);
     }
-    self->ring_tail = (self->ring_tail + to_copy) % USB_AUDIO_SPEAKER_RING_SIZE;
+    self->ring_tail = (self->ring_tail + to_copy) % self->ring_len;
     self->ring_count -= to_copy;
 
     if (to_copy < half) {
diff --git a/shared-module/usb_audio/USBSpeaker.h b/shared-module/usb_audio/USBSpeaker.h
index 8c06cff519d..1483ff89085 100644
--- a/shared-module/usb_audio/USBSpeaker.h
+++ b/shared-module/usb_audio/USBSpeaker.h
@@ -22,21 +22,6 @@
 // comfortably inside the ring.
 #define USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER (128)
 
-// Bytes per audio frame in the negotiated UAC2 format (mono 16-bit for v1).
-#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_N_BYTES_PER_SAMPLE * USB_AUDIO_N_CHANNELS)
-
-// Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
-// audiocore.RawSample's convention where base.max_buffer_length is the whole
-// buffer and get_buffer() returns half of it.
-#define USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE (2 * USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER * USB_AUDIO_SPEAKER_BYTES_PER_FRAME)
-
-// Host -> board receive ring size. Mirrors CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ
-// (16 * the full-speed OUT wMaxPacketSize) but is spelled out from the format
-// constants so this struct definition stays free of the TinyUSB headers. A
-// MP_STATIC_ASSERT in USBSpeaker.c checks the two stay equal.
-#define USB_AUDIO_SPEAKER_OUT_PACKET_SIZE ((USB_AUDIO_MAX_SAMPLE_RATE / 1000 + 1) * USB_AUDIO_SPEAKER_BYTES_PER_FRAME)
-#define USB_AUDIO_SPEAKER_RING_SIZE (16 * USB_AUDIO_SPEAKER_OUT_PACKET_SIZE)
-
 typedef struct usb_audio_usbspeaker_obj {
     // First member so the object can be used directly as an audiosample source.
     audiosample_base_t base;
@@ -45,13 +30,14 @@ typedef struct usb_audio_usbspeaker_obj {
     // background task via usb_audio_usbspeaker_background_drain() and drained by
     // get_buffer(). Single producer (task), single consumer (output DMA ISR);
     // see the concurrency notes in USBSpeaker.c.
-    uint8_t ring[USB_AUDIO_SPEAKER_RING_SIZE];
+    uint8_t *ring;
+    size_t ring_len;
     size_t ring_head;   // next write offset
     size_t ring_tail;   // next read offset
     size_t ring_count;  // valid bytes currently in the ring
 
     // Owned double-buffer returned to the output backend by get_buffer().
-    uint8_t output_buffer[USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE];
+    uint8_t *output_buffer;
     uint8_t output_index;  // 0 or 1: which half get_buffer() fills next
 } usb_audio_usbspeaker_obj_t;
 
diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index 5964b8acf78..113f503ee66 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -20,6 +20,9 @@
 #include "supervisor/shared/tick.h"
 #include "tusb.h"
 
+int16_t *usb_audio_mic_samples;
+size_t usb_audio_mic_samples_len;
+
 static bool usb_audio_is_enabled = false;
 
 // The host opens each AudioStreaming interface independently (alt 0 = idle, alt 1
@@ -41,14 +44,24 @@ bool usb_audio_microphone_enabled;
 bool usb_audio_speaker_enabled;
 
 // Audio control state surfaced to the host. One extra entry for the master channel 0.
-static int8_t usb_audio_mute[USB_AUDIO_N_CHANNELS + 1];
-static int16_t usb_audio_volume[USB_AUDIO_N_CHANNELS + 1];
+static int8_t usb_audio_mute[USB_AUDIO_MAX_CHANNELS + 1];
+static int16_t usb_audio_volume[USB_AUDIO_MAX_CHANNELS + 1];
 
 bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, mp_int_t bits_per_sample, bool microphone, bool speaker) {
     if (tud_connected()) {
         return false;
     }
 
+    // One scratch chunk (1 ms at the sample rate); we loop until the FIFO reaches
+    // the setpoint.
+    usb_audio_mic_samples_len = sample_rate / 1000 * channel_count * USB_AUDIO_N_BYTES_PER_SAMPLE;
+    usb_audio_mic_samples = (int16_t *)m_malloc_without_collect(usb_audio_mic_samples_len);
+    if (usb_audio_mic_samples == NULL) {
+        m_malloc_fail(usb_audio_mic_samples_len);
+        return false;
+    }
+    memset(usb_audio_mic_samples, 0, usb_audio_mic_samples_len);
+
     usb_audio_sample_rate = sample_rate;
     usb_audio_channel_count = channel_count;
     usb_audio_bits_per_sample = bits_per_sample;
@@ -126,25 +139,25 @@ void usb_audio_setup_singletons(void) {
         speaker;
 }
 
-// Hand-rolled UAC2 mono speaker (host -> board) descriptor WITHOUT an async
-// feedback endpoint. This mirrors TinyUSB's TUD_AUDIO_SPEAKER_MONO_FB_DESCRIPTOR
+// Hand-rolled UAC2 speaker (host -> board) descriptor WITHOUT an async
+// feedback endpoint. This mirrors TinyUSB's TUD_AUDIO_SPEAKER_STEREO_FB_DESCRIPTOR
 // (lib/tinyusb/src/device/usbd.h) but drops the trailing feedback endpoint, so
 // the streaming alt-setting declares a single OUT endpoint (_nEPs = 0x01). The
 // entity IDs match the mic descriptor (see usb_audio_descriptors.h); only the
 // terminal roles reverse: the input terminal is the USB-streaming side and the
 // output terminal is the desktop speaker, and the AS interface links the input
 // terminal (0x01). Async feedback for true clock matching is a later step.
-#define USB_AUDIO_SPEAKER_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
+#define USB_AUDIO_SPEAKER_ONE_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
     /* Standard Interface Association Descriptor (IAD) */ \
     TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
     /* Standard AC Interface Descriptor(4.7.1) */ \
     TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
     /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
-    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_DESKTOP_SPEAKER, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_DESKTOP_SPEAKER, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
     /* Clock Source Descriptor(4.7.2.1) */ \
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -154,7 +167,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -162,10 +175,103 @@ void usb_audio_setup_singletons(void) {
     /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
     TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
 
+#define USB_AUDIO_SPEAKER_TWO_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
+    /* Standard Interface Association Descriptor (IAD) */ \
+    TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
+    /* Standard AC Interface Descriptor(4.7.1) */ \
+    TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
+    /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
+    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_DESKTOP_SPEAKER, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+    /* Clock Source Descriptor(4.7.2.1) */ \
+    TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
+    /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
+    TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
+    /* Feature Unit Descriptor(4.7.2.8) */ \
+    TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+    /* Standard AS Interface Descriptor(4.9.1) -- alt 0, zero bandwidth */ \
+    TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00), \
+    /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
+    TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
+    /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
+    TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
+    /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t)((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
+    /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
+    TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
+
+// Hand-rolled UAC2 microphone (board -> host) descriptor WITHOUT an async
+// feedback endpoint. This mirrors TinyUSB's TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR
+// (lib/tinyusb/src/device/usbd.h) but drops the trailing feedback endpoint, so
+// the streaming alt-setting declares a single IN endpoint (_nEPs = 0x00). Async
+// feedback for true clock matching is a later step.
+#define USB_AUDIO_MIC_ONE_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
+  /* Standard Interface Association Descriptor (IAD) */ \
+  TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
+  /* Standard AC Interface Descriptor(4.7.1) */ \
+  TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
+  /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
+  TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_MICROPHONE, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+  /* Clock Source Descriptor(4.7.2.1) */ \
+  TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
+  /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
+  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
+  TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
+  /* Feature Unit Descriptor(4.7.2.8) */ \
+  TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+  /* Standard AS Interface Descriptor(4.9.1) */ \
+  /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */ \
+  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
+  /* Standard AS Interface Descriptor(4.9.1) */ \
+  /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
+  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
+  /* Class-Specific AS Interface Descriptor(4.9.2) */ \
+  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
+  TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
+  /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
+  TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
+  /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
+  TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
+
+#define USB_AUDIO_MIC_TWO_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
+  /* Standard Interface Association Descriptor (IAD) */ \
+  TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
+  /* Standard AC Interface Descriptor(4.7.1) */ \
+  TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
+  /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
+  TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_MICROPHONE, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+  /* Clock Source Descriptor(4.7.2.1) */ \
+  TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
+  /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
+  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
+  TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
+  /* Feature Unit Descriptor(4.7.2.8) */ \
+  TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+  /* Standard AS Interface Descriptor(4.9.1) */ \
+  /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */ \
+  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
+  /* Standard AS Interface Descriptor(4.9.1) */ \
+  /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
+  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
+  /* Class-Specific AS Interface Descriptor(4.9.2) */ \
+  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
+  TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
+  /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
+  TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
+  /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
+  TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
+
 // Hand-rolled UAC2 mono headset (microphone + speaker both enabled): one audio function
 // presenting both a speaker (host -> board OUT) and a microphone (board -> host
 // IN) at once. This combines USB_AUDIO_SPEAKER_DESCRIPTOR's speaker chain with
-// TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR's mic chain under a single IAD. The two chains
+// USB_AUDIO_MIC_DESCRIPTOR's mic chain under a single IAD. The two chains
 // must use distinct entity IDs (USB_AUDIO_HS_ENTITY_*; see usb_audio_descriptors.h)
 // because they live in the same AudioControl interface, and they share one clock
 // source. The function spans three interfaces: AudioControl (_itfnum), the
@@ -183,14 +289,14 @@ void usb_audio_setup_singletons(void) {
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ 0x00, /*_stridx*/ 0x00), \
     /* --- Speaker chain (host -> board) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x00, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* --- Mic chain (board -> host) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- generic microphone */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- USB streaming out to the host */ \
@@ -201,7 +307,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the speaker input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -214,7 +320,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one IN endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 2), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the mic output terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -238,9 +344,17 @@ size_t usb_audio_descriptor_length(void) {
         return USB_AUDIO_HEADSET_DESC_LEN;
     }
     if (usb_audio_direction_is_output()) {
-        return USB_AUDIO_SPEAKER_DESC_LEN;
+        if (usb_audio_channel_count == 1) {
+            return USB_AUDIO_SPEAKER_ONE_CH_DESC_LEN;
+        } else {
+            return USB_AUDIO_SPEAKER_TWO_CH_DESC_LEN;
+        }
+    }
+    if (usb_audio_channel_count == 1) {
+        return USB_AUDIO_MIC_ONE_CH_DESC_LEN;
+    } else {
+        return USB_AUDIO_MIC_TWO_CH_DESC_LEN;
     }
-    return TUD_AUDIO_MIC_ONE_CH_DESC_LEN;
 }
 
 size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string) {
@@ -268,6 +382,8 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         const uint8_t ep_in = descriptor_counts->current_endpoint + 1;
 
         usb_add_interface_string(*current_interface_string, "CircuitPython Headset");
+        (*current_interface_string)++;
+        
         const uint8_t usb_audio_descriptor[] = {
             USB_AUDIO_HEADSET_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
@@ -283,7 +399,6 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
         usb_audio_mic_as_itf = descriptor_counts->current_interface + 2;
 
-        (*current_interface_string)++;
         // One IAD wrapping an AudioControl + two AudioStreaming interfaces, plus
         // one OUT and one IN endpoint.
         descriptor_counts->current_interface += 3;
@@ -298,57 +413,105 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
 
     if (usb_audio_direction_is_output()) {
         usb_add_interface_string(*current_interface_string, "CircuitPython Speaker");
+        (*current_interface_string)++;
+
+        // The AudioStreaming interface follows the AudioControl interface.
+        usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
+
+        if (usb_audio_channel_count == 1) {
+            const uint8_t usb_audio_descriptor[] = {
+                USB_AUDIO_SPEAKER_ONE_CH_DESCRIPTOR(
+                    /*_itfnum*/ descriptor_counts->current_interface,
+                    /*_stridx*/ *current_interface_string,
+                    /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+                    /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
+                    /*_epout*/ iso_ep_num,
+                    /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
+            };
+
+            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
+            descriptor_counts->current_interface += 2;
+            if (!forced_iso_ep) {
+                descriptor_counts->num_out_endpoints++;
+                descriptor_counts->current_endpoint++;
+            }
+
+            memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
+
+            return sizeof(usb_audio_descriptor);
+        } else {
+            const uint8_t usb_audio_descriptor[] = {
+                USB_AUDIO_SPEAKER_TWO_CH_DESCRIPTOR(
+                    /*_itfnum*/ descriptor_counts->current_interface,
+                    /*_stridx*/ *current_interface_string,
+                    /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+                    /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
+                    /*_epout*/ iso_ep_num,
+                    /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
+            };
+
+            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
+            descriptor_counts->current_interface += 3;
+            if (!forced_iso_ep) {
+                descriptor_counts->num_out_endpoints += 2;
+                descriptor_counts->current_endpoint += 2;
+            }
+
+            memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
+
+            return sizeof(usb_audio_descriptor);
+        }
+    }
+
+    usb_add_interface_string(*current_interface_string, "CircuitPython Microphone");
+    (*current_interface_string)++;
+
+    // The AudioStreaming interface follows the AudioControl interface.
+    usb_audio_mic_as_itf = descriptor_counts->current_interface + 1;
+
+    if (usb_audio_channel_count == 2) {
         const uint8_t usb_audio_descriptor[] = {
-            USB_AUDIO_SPEAKER_DESCRIPTOR(
+            USB_AUDIO_MIC_ONE_CH_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
                 /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-                /*_epout*/ iso_ep_num,
-                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
+                /*_epin*/ iso_ep_num | 0x80,
+                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
         };
 
-        // The AudioStreaming interface follows the AudioControl interface.
-        usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
-
-        (*current_interface_string)++;
-        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
+        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
         descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
-            descriptor_counts->num_out_endpoints++;
+            descriptor_counts->num_in_endpoints++;
             descriptor_counts->current_endpoint++;
         }
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
         return sizeof(usb_audio_descriptor);
-    }
+    } else {
+        const uint8_t usb_audio_descriptor[] = {
+            USB_AUDIO_MIC_TWO_CH_DESCRIPTOR(
+                /*_itfnum*/ descriptor_counts->current_interface,
+                /*_stridx*/ *current_interface_string,
+                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+                /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
+                /*_epin*/ iso_ep_num | 0x80,
+                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
+        };
 
-    usb_add_interface_string(*current_interface_string, "CircuitPython Microphone");
-    const uint8_t usb_audio_descriptor[] = {
-        TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR(
-            /*_itfnum*/ descriptor_counts->current_interface,
-            /*_stridx*/ *current_interface_string,
-            /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
-            /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-            /*_epin*/ iso_ep_num | 0x80,
-            /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
-    };
+        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
+        descriptor_counts->current_interface += 3;
+        if (!forced_iso_ep) {
+            descriptor_counts->num_in_endpoints += 2;
+            descriptor_counts->current_endpoint += 2;
+        }
 
-    // The AudioStreaming interface follows the AudioControl interface.
-    usb_audio_mic_as_itf = descriptor_counts->current_interface + 1;
+        memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
-    (*current_interface_string)++;
-    // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
-    descriptor_counts->current_interface += 2;
-    if (!forced_iso_ep) {
-        descriptor_counts->num_in_endpoints++;
-        descriptor_counts->current_endpoint++;
+        return sizeof(usb_audio_descriptor);
     }
-
-    memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
-
-    return sizeof(usb_audio_descriptor);
 }
 
 // --------------------------------------------------------------------+
@@ -397,24 +560,20 @@ static void usb_audio_microphone_task(void) {
     tu_fifo_t *ep_in_ff = tud_audio_get_ep_in_ff();
     uint16_t const target = tu_fifo_depth(ep_in_ff) / 2;
 
-    // One scratch chunk (1 ms at the max rate); we loop until the FIFO reaches
-    // the setpoint. Sized for the highest rate enable() accepts.
-    static int16_t samples[USB_AUDIO_MAX_SAMPLE_RATE / 1000 * USB_AUDIO_N_CHANNELS];
-
     uint16_t count;
     while ((count = tu_fifo_count(ep_in_ff)) < target) {
         size_t want = target - count;
-        if (want > sizeof(samples)) {
-            want = sizeof(samples);
+        if (want > usb_audio_mic_samples_len) {
+            want = usb_audio_mic_samples_len;
         }
 
         // Pull the next chunk from whichever USBMicrophone is playing.
         bool underran = false;
-        size_t filled = usb_audio_usbmicrophone_background_fill((uint8_t *)samples, want);
+        size_t filled = usb_audio_usbmicrophone_background_fill((uint8_t *)usb_audio_mic_samples, want);
         if (filled == 0) {
             // No source attached, paused, or fully drained: keep the endpoint
             // alive with silence so the host never sees a starved stream.
-            memset((uint8_t *)samples, 0, want);
+            memset((uint8_t *)usb_audio_mic_samples, 0, want);
         } else if (filled < want) {
             // The source momentarily underran. Send just what it produced and
             // let the FIFO cushion ride until it catches up next pass, rather
@@ -423,7 +582,7 @@ static void usb_audio_microphone_task(void) {
             underran = true;
         }
 
-        if (tud_audio_write((uint8_t *)samples, (uint16_t)want) == 0) {
+        if (tud_audio_write((uint8_t *)usb_audio_mic_samples, (uint16_t)want) == 0) {
             break;  // FIFO unexpectedly full / host not ready
         }
         if (underran) {
@@ -496,10 +655,10 @@ bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
 
     // A headset exposes a feature unit per direction; the speaker's id matches the
     // single-direction USB_AUDIO_ENTITY_FEATURE_UNIT, the mic adds a second one.
-    // Mute/volume state is shared across them (mono, cosmetic for now).
+    // Mute/volume state is shared across them.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_N_CHANNELS) {
+        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
@@ -537,7 +696,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
         switch (ctrlSel) {
             case AUDIO_TE_CTRL_CONNECTOR: {
                 audio_desc_channel_cluster_t ret;
-                ret.bNrChannels = USB_AUDIO_N_CHANNELS;
+                ret.bNrChannels = usb_audio_channel_count;
                 ret.bmChannelConfig = (audio_channel_config_t)0;
                 ret.iChannelNames = 0;
                 return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &ret, sizeof(ret));
@@ -550,7 +709,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Feature unit (mute/volume) for either the speaker or mic chain.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_N_CHANNELS) {
+        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
diff --git a/shared-module/usb_audio/usb_audio_descriptors.h b/shared-module/usb_audio/usb_audio_descriptors.h
index 8b297c3218f..d94c8acabdf 100644
--- a/shared-module/usb_audio/usb_audio_descriptors.h
+++ b/shared-module/usb_audio/usb_audio_descriptors.h
@@ -27,10 +27,10 @@ size_t usb_audio_descriptor_length(void);
 // The isochronous IN endpoint's wMaxPacketSize in the USB descriptor is computed
 // for this rate, so it is the highest rate usb_audio.enable() will accept.
 #define USB_AUDIO_MAX_SAMPLE_RATE (48000)
+#define USB_AUDIO_MAX_CHANNELS (2)
 
-// 16-bit signed LE PCM, mono.
+// 16-bit signed LE PCM.
 #define USB_AUDIO_N_BYTES_PER_SAMPLE (2)
-#define USB_AUDIO_N_CHANNELS (2)
 #define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_N_BYTES_PER_SAMPLE * 8)
 
 // Endpoint number for the single isochronous audio data endpoint. Most device
@@ -45,7 +45,7 @@ size_t usb_audio_descriptor_length(void);
 #define USB_AUDIO_ISO_EP_NUM (0)
 #endif
 
-// Fixed UAC2 entity IDs baked into TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR and the
+// Fixed UAC2 entity IDs baked into USB_AUDIO_MIC_DESCRIPTOR and the
 // hand-rolled speaker descriptor (USB_AUDIO_SPEAKER_DESCRIPTOR in __init__.c).
 // The speaker reuses the same IDs as the mic; only the terminal roles reverse
 // (input terminal = USB streaming, output terminal = desktop speaker).
@@ -68,21 +68,71 @@ size_t usb_audio_descriptor_length(void);
 #define USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT (0x06)
 #define USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL (0x07)  // USB streaming out to host
 
-// Length of the no-feedback mono speaker descriptor. It uses the same set of
-// sub-descriptors as TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR (one isochronous data
+// Length of the no-feedback speaker descriptor. It uses the same set of
+// sub-descriptors as USB_AUDIO_MIC_DESCRIPTOR (except one isochronous data
 // endpoint, no feedback endpoint), so this is identical to
-// TUD_AUDIO_MIC_ONE_CH_DESC_LEN -- but spell it out independently so the two
+// USB_AUDIO_MIC_DESC_LEN -- but spell it out independently so the two
 // can diverge later (e.g. stereo) without silently mis-sizing the descriptor.
 // These TUD_AUDIO_DESC_*_LEN macros come from TinyUSB's usbd.h; this expression
 // is only expanded where that header is already included (never at the point
 // tusb_config.h includes us), so the header stays dependency-free.
-#define USB_AUDIO_SPEAKER_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+#define USB_AUDIO_SPEAKER_ONE_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
     + TUD_AUDIO_DESC_STD_AC_LEN \
     + TUD_AUDIO_DESC_CS_AC_LEN \
     + TUD_AUDIO_DESC_CLK_SRC_LEN \
+    /* speaker chain: USB-streaming input terminal -> feature unit -> speaker */ \
     + TUD_AUDIO_DESC_INPUT_TERM_LEN \
     + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
     + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
+    /* speaker AudioStreaming interface (alt 0 + alt 1 with OUT endpoint) */ \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_CS_AS_INT_LEN \
+    + TUD_AUDIO_DESC_TYPE_I_FORMAT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
+    + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
+
+#define USB_AUDIO_SPEAKER_TWO_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+    + TUD_AUDIO_DESC_STD_AC_LEN \
+    + TUD_AUDIO_DESC_CS_AC_LEN \
+    + TUD_AUDIO_DESC_CLK_SRC_LEN \
+    /* speaker chain: USB-streaming input terminal -> feature unit -> speaker */ \
+    + TUD_AUDIO_DESC_INPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN \
+    /* speaker AudioStreaming interface (alt 0 + alt 1 with OUT endpoint) */ \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_CS_AS_INT_LEN \
+    + TUD_AUDIO_DESC_TYPE_I_FORMAT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
+    + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
+
+#define USB_AUDIO_MIC_ONE_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+    + TUD_AUDIO_DESC_STD_AC_LEN \
+    + TUD_AUDIO_DESC_CS_AC_LEN \
+    + TUD_AUDIO_DESC_CLK_SRC_LEN \
+    /* mic chain: microphone input terminal -> feature unit -> USB-streaming out */ \
+    + TUD_AUDIO_DESC_INPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
+    /* mic AudioStreaming interface (alt 0 + alt 1 with IN endpoint) */ \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
+    + TUD_AUDIO_DESC_CS_AS_INT_LEN \
+    + TUD_AUDIO_DESC_TYPE_I_FORMAT_LEN \
+    + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
+    + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
+
+#define USB_AUDIO_MIC_TWO_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+    + TUD_AUDIO_DESC_STD_AC_LEN \
+    + TUD_AUDIO_DESC_CS_AC_LEN \
+    + TUD_AUDIO_DESC_CLK_SRC_LEN \
+    /* mic chain: microphone input terminal -> feature unit -> USB-streaming out */ \
+    + TUD_AUDIO_DESC_INPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
+    + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN \
+    /* mic AudioStreaming interface (alt 0 + alt 1 with IN endpoint) */ \
     + TUD_AUDIO_DESC_STD_AS_INT_LEN \
     + TUD_AUDIO_DESC_STD_AS_INT_LEN \
     + TUD_AUDIO_DESC_CS_AS_INT_LEN \
diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
index a10cd712226..12f32988bc2 100644
--- a/supervisor/shared/usb/tusb_config.h
+++ b/supervisor/shared/usb/tusb_config.h
@@ -142,9 +142,9 @@ extern "C" {
 
 #define CFG_TUD_AUDIO_ENABLE_EP_IN                  1
 #define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_N_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_MAX_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
 // Deep software FIFO so the 1 ms refill keeps clear of the underrun floor.
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ        (16 * CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
 
@@ -154,9 +154,9 @@ extern "C" {
 // IN sizing above.
 #define CFG_TUD_AUDIO_ENABLE_EP_OUT                 1
 #define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_N_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_MAX_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
 // Deep software FIFO so the 1 ms drain keeps clear of the overrun ceiling.
 #define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ       (16 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
 #endif

From ff4b108b746a68122ea1bf6d1447c448ffb11b7a Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 18:09:29 -0500
Subject: [PATCH 04/11] Fix descriptor declaration

---
 shared-module/usb_audio/__init__.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index 113f503ee66..add1ec1c972 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -382,7 +382,6 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         const uint8_t ep_in = descriptor_counts->current_endpoint + 1;
 
         usb_add_interface_string(*current_interface_string, "CircuitPython Headset");
-        (*current_interface_string)++;
         
         const uint8_t usb_audio_descriptor[] = {
             USB_AUDIO_HEADSET_DESCRIPTOR(
@@ -399,6 +398,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
         usb_audio_mic_as_itf = descriptor_counts->current_interface + 2;
 
+        (*current_interface_string)++;
         // One IAD wrapping an AudioControl + two AudioStreaming interfaces, plus
         // one OUT and one IN endpoint.
         descriptor_counts->current_interface += 3;
@@ -413,7 +413,6 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
 
     if (usb_audio_direction_is_output()) {
         usb_add_interface_string(*current_interface_string, "CircuitPython Speaker");
-        (*current_interface_string)++;
 
         // The AudioStreaming interface follows the AudioControl interface.
         usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
@@ -429,6 +428,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
                     /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
             };
 
+            (*current_interface_string)++;
             // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
             descriptor_counts->current_interface += 2;
             if (!forced_iso_ep) {
@@ -450,8 +450,9 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
                     /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
             };
 
-            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
-            descriptor_counts->current_interface += 3;
+            (*current_interface_string)++;
+            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two OUT endpoints.
+            descriptor_counts->current_interface += 2;
             if (!forced_iso_ep) {
                 descriptor_counts->num_out_endpoints += 2;
                 descriptor_counts->current_endpoint += 2;
@@ -464,12 +465,11 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
     }
 
     usb_add_interface_string(*current_interface_string, "CircuitPython Microphone");
-    (*current_interface_string)++;
 
     // The AudioStreaming interface follows the AudioControl interface.
     usb_audio_mic_as_itf = descriptor_counts->current_interface + 1;
 
-    if (usb_audio_channel_count == 2) {
+    if (usb_audio_channel_count == 1) {
         const uint8_t usb_audio_descriptor[] = {
             USB_AUDIO_MIC_ONE_CH_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
@@ -480,6 +480,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
                 /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
         };
 
+        (*current_interface_string)++;
         // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
         descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
@@ -501,8 +502,9 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
                 /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
         };
 
-        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
-        descriptor_counts->current_interface += 3;
+        (*current_interface_string)++;
+        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two IN endpoints.
+        descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
             descriptor_counts->num_in_endpoints += 2;
             descriptor_counts->current_endpoint += 2;

From a0a6b79701179cf5f0f3a7321826e98a6d4797ad Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 18:17:29 -0500
Subject: [PATCH 05/11] Revert dynamic ring buffer

---
 shared-module/usb_audio/USBSpeaker.c | 18 +++++-------------
 shared-module/usb_audio/USBSpeaker.h | 13 +++++++++++--
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/shared-module/usb_audio/USBSpeaker.c b/shared-module/usb_audio/USBSpeaker.c
index 63c75dbf5b5..58601c69ed2 100644
--- a/shared-module/usb_audio/USBSpeaker.c
+++ b/shared-module/usb_audio/USBSpeaker.c
@@ -15,6 +15,11 @@
 
 #include "tusb.h"
 
+// The ring is sized independently of the TinyUSB headers (see USBSpeaker.h);
+// check it still matches the OUT endpoint's software FIFO so the push side can be
+// reasoned about against the USB plumbing.
+MP_STATIC_ASSERT(USB_AUDIO_SPEAKER_RING_SIZE == CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ);
+
 // Only one speaker can be fed by the single USB OUT endpoint at a time. This
 // points at the most recently constructed USBSpeaker, or NULL when none exists,
 // mirroring active_microphone in USBMicrophone.c. The USB background task pushes
@@ -43,19 +48,6 @@ void common_hal_usb_audio_usbspeaker_construct(usb_audio_usbspeaker_obj_t *self)
     }
     memset(self->output_buffer, 0, self->base.max_buffer_length);
 
-    // The ring is sized independently of the TinyUSB headers; check it still
-    // matches the OUT endpoint's software FIFO so the push side can be reasoned
-    // about against the USB plumbing.
-    self->ring_len = 16 * ((usb_audio_sample_rate / 1000 + 1) * (USB_AUDIO_N_BYTES_PER_SAMPLE * usb_audio_channel_count));
-    assert(self->ring_len == CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ);
-
-    self->ring = m_malloc_without_collect(self->ring_len);
-    if (self->ring == NULL) {
-        common_hal_usb_audio_usbspeaker_deinit(self);
-        m_malloc_fail(self->ring_len);
-    }
-    memset(self->ring, 0, self->ring_len);
-
     self->ring_head = 0;
     self->ring_tail = 0;
     self->ring_count = 0;
diff --git a/shared-module/usb_audio/USBSpeaker.h b/shared-module/usb_audio/USBSpeaker.h
index 1483ff89085..d1694cd4745 100644
--- a/shared-module/usb_audio/USBSpeaker.h
+++ b/shared-module/usb_audio/USBSpeaker.h
@@ -22,6 +22,16 @@
 // comfortably inside the ring.
 #define USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER (128)
 
+// Bytes per audio frame in the negotiated UAC2 format (mono 16-bit for v1).
+#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_N_BYTES_PER_SAMPLE * USB_AUDIO_N_CHANNELS)
+
+// Host -> board receive ring size. Mirrors CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ
+// (16 * the full-speed OUT wMaxPacketSize) but is spelled out from the format
+// constants so this struct definition stays free of the TinyUSB headers. A
+// MP_STATIC_ASSERT in USBSpeaker.c checks the two stay equal.
+#define USB_AUDIO_SPEAKER_OUT_PACKET_SIZE ((USB_AUDIO_MAX_SAMPLE_RATE / 1000 + 1) * USB_AUDIO_SPEAKER_BYTES_PER_FRAME)
+#define USB_AUDIO_SPEAKER_RING_SIZE (16 * USB_AUDIO_SPEAKER_OUT_PACKET_SIZE)
+
 typedef struct usb_audio_usbspeaker_obj {
     // First member so the object can be used directly as an audiosample source.
     audiosample_base_t base;
@@ -30,8 +40,7 @@ typedef struct usb_audio_usbspeaker_obj {
     // background task via usb_audio_usbspeaker_background_drain() and drained by
     // get_buffer(). Single producer (task), single consumer (output DMA ISR);
     // see the concurrency notes in USBSpeaker.c.
-    uint8_t *ring;
-    size_t ring_len;
+    uint8_t ring[USB_AUDIO_SPEAKER_RING_SIZE];
     size_t ring_head;   // next write offset
     size_t ring_tail;   // next read offset
     size_t ring_count;  // valid bytes currently in the ring

From 2d9d805ab734b5125919262ac607fcd035826127 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 22:41:10 -0500
Subject: [PATCH 06/11] Assume stereo operation

---
 shared-bindings/usb_audio/USBMicrophone.c     |   1 +
 shared-bindings/usb_audio/__init__.c          |  20 +-
 shared-module/usb_audio/USBMicrophone.c       |  17 +-
 shared-module/usb_audio/USBSpeaker.c          |  71 +++---
 shared-module/usb_audio/USBSpeaker.h          |   7 +-
 shared-module/usb_audio/__init__.c            | 226 +++++-------------
 shared-module/usb_audio/__init__.h            |   3 +-
 .../usb_audio/usb_audio_descriptors.h         |  44 +---
 supervisor/shared/usb/tusb_config.h           |   8 +-
 9 files changed, 133 insertions(+), 264 deletions(-)

diff --git a/shared-bindings/usb_audio/USBMicrophone.c b/shared-bindings/usb_audio/USBMicrophone.c
index ff53d812e49..c66c78942dd 100644
--- a/shared-bindings/usb_audio/USBMicrophone.c
+++ b/shared-bindings/usb_audio/USBMicrophone.c
@@ -12,6 +12,7 @@
 #include "shared-bindings/usb_audio/USBMicrophone.h"
 #include "shared-bindings/util.h"
 #include "shared-module/usb_audio/__init__.h"
+#include "shared-module/usb_audio/usb_audio_descriptors.h"
 
 //| class USBMicrophone:
 //|     """Streams an audio sample to the host computer as a USB Audio Class microphone.
diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 77c3201fcb5..00ec82f10ae 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -19,7 +19,7 @@
 //| Audio Class (UAC2) microphone: the board is the audio *source* and streams
 //| samples to the host over a USB isochronous IN endpoint.
 //|
-//| This mode requires 1 (mono) or 2 (stereo / bidirectional) IN endpoint and 2 interfaces.
+//| This mode requires 2 IN endpoints and 2 interfaces.
 //| Generally, microcontrollers have a limit on the number of endpoints. If you exceed the number
 //| of endpoints, CircuitPython will automatically enter Safe Mode. Even in this case, you may be
 //| able to enable USB audio by also disabling other USB functions, such as
@@ -32,7 +32,7 @@
 //|
 //|     # boot.py
 //|     import usb_audio
-//|     usb_audio.enable(sample_rate=16000, channel_count=1, bits_per_sample=16)
+//|     usb_audio.enable(sample_rate=16000, bits_per_sample=16)
 //|
 //| .. code-block:: py
 //|
@@ -64,9 +64,6 @@
 //| The ``sample_rate`` and ``channel_count`` of the sample played must match the values passed to `enable`,
 //| and the sample must be 16-bit signed; otherwise ``play`` raises a ``ValueError``.
 //|
-//| If both speaker and headphone features are enabled (bidirectional), only mono operation is
-//| permitted.
-//|
 //| This interface is experimental and may change without notice even in stable
 //| versions of CircuitPython."""
 //|
@@ -86,7 +83,6 @@
 //| def enable(
 //|     sample_rate: int = 16000,
 //|     channel_count: int = 1,
-//|     bits_per_sample: int = 16,
 //|     microphone: bool = True,
 //|     speaker: bool = False,
 //| ) -> None:
@@ -105,11 +101,10 @@
 //|
 //|
 static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    enum { ARG_sample_rate, ARG_channel_count, ARG_bits_per_sample, ARG_microphone, ARG_speaker };
+    enum { ARG_sample_rate, ARG_channel_count, ARG_microphone, ARG_speaker };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_sample_rate, MP_ARG_INT, { .u_int = 16000 } },
         { MP_QSTR_channel_count, MP_ARG_INT, { .u_int = 1 } },
-        { MP_QSTR_bits_per_sample, MP_ARG_INT, { .u_int = 16 } },
         { MP_QSTR_microphone, MP_ARG_BOOL, { .u_bool = true } },
         { MP_QSTR_speaker, MP_ARG_BOOL, { .u_bool = false } },
     };
@@ -117,8 +112,7 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     mp_int_t sample_rate = mp_arg_validate_int_range(args[ARG_sample_rate].u_int, 1, USB_AUDIO_MAX_SAMPLE_RATE, MP_QSTR_sample_rate);
-    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_MAX_CHANNELS, MP_QSTR_channel_count);
-    mp_int_t bits_per_sample = mp_arg_validate_int(args[ARG_bits_per_sample].u_int, USB_AUDIO_BITS_PER_SAMPLE, MP_QSTR_bits_per_sample);
+    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_N_CHANNELS, MP_QSTR_channel_count);
     bool microphone = args[ARG_microphone].u_bool;
     bool speaker = args[ARG_speaker].u_bool;
 
@@ -126,11 +120,7 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
         mp_raise_ValueError(MP_ERROR_TEXT("At least one of microphone and speaker must be enabled"));
     }
 
-    if (microphone && speaker && channel_count == 2) {
-        mp_raise_ValueError(MP_ERROR_TEXT("Only mono operation is supported when microphone and speaker are both enabled"));
-    }
-
-    if (!shared_module_usb_audio_enable(sample_rate, channel_count, bits_per_sample, microphone, speaker)) {
+    if (!shared_module_usb_audio_enable(sample_rate, channel_count, microphone, speaker)) {
         mp_raise_RuntimeError(MP_ERROR_TEXT("Cannot change USB devices now"));
     }
 
diff --git a/shared-module/usb_audio/USBMicrophone.c b/shared-module/usb_audio/USBMicrophone.c
index c9245b2edb2..a1228ad1c64 100644
--- a/shared-module/usb_audio/USBMicrophone.c
+++ b/shared-module/usb_audio/USBMicrophone.c
@@ -11,6 +11,7 @@
 
 #include "shared-bindings/usb_audio/USBMicrophone.h"
 #include "shared-module/usb_audio/__init__.h"
+#include "shared-module/usb_audio/usb_audio_descriptors.h"
 #include "shared-module/audiocore/__init__.h"
 
 // Only one microphone may feed the single USB IN endpoint at a time. This points
@@ -53,7 +54,7 @@ void common_hal_usb_audio_usbmicrophone_play(usb_audio_usbmicrophone_obj_t *self
     if (audiosample_get_channel_count(sample_base) != usb_audio_channel_count) {
         mp_raise_ValueError_varg(MP_ERROR_TEXT("The sample's %q does not match"), MP_QSTR_channel_count);
     }
-    if (audiosample_get_bits_per_sample(sample_base) != usb_audio_bits_per_sample) {
+    if (audiosample_get_bits_per_sample(sample_base) != USB_AUDIO_BITS_PER_SAMPLE) {
         mp_raise_ValueError_varg(MP_ERROR_TEXT("The sample's %q does not match"), MP_QSTR_bits_per_sample);
     }
     if (!sample_base->samples_signed) {
@@ -138,8 +139,18 @@ size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
             }
         }
 
-        size_t n = MIN(self->buffer_length, max_bytes - filled);
-        memcpy(out + filled, self->buffer, n);
+        size_t n;
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+            n = MIN(self->buffer_length, max_bytes - filled);
+            memcpy(out + filled, self->buffer, n);
+        } else {
+            n = MIN(self->buffer_length << 1, max_bytes - filled);
+            int16_t *word_buffer = (int16_t *)self->buffer;
+            int16_t *word_out = (int16_t *)(out + filled);
+            for (size_t i = 0; i < n / USB_AUDIO_N_BYTES_PER_SAMPLE; i++) {
+                word_out[i] = word_buffer[i >> 1];
+            }
+        }
         self->buffer += n;
         self->buffer_length -= n;
         filled += n;
diff --git a/shared-module/usb_audio/USBSpeaker.c b/shared-module/usb_audio/USBSpeaker.c
index 58601c69ed2..310eb3cd7d2 100644
--- a/shared-module/usb_audio/USBSpeaker.c
+++ b/shared-module/usb_audio/USBSpeaker.c
@@ -32,22 +32,12 @@ void common_hal_usb_audio_usbspeaker_construct(usb_audio_usbspeaker_obj_t *self)
     // format we present is 16-bit signed LE PCM, which is exactly what the
     // CircuitPython audio pipeline carries, so no conversion is needed.
     self->base.sample_rate = usb_audio_sample_rate;
-    self->base.bits_per_sample = usb_audio_bits_per_sample;
+    self->base.bits_per_sample = USB_AUDIO_BITS_PER_SAMPLE;
     self->base.channel_count = usb_audio_channel_count;
     self->base.samples_signed = true;
     self->base.single_buffer = false;
+    self->base.max_buffer_length = USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE;
     
-    // Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
-    // audiocore.RawSample's convention where base.max_buffer_length is the whole
-    // buffer and get_buffer() returns half of it.
-    self->base.max_buffer_length = (2 * USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER * USB_AUDIO_N_BYTES_PER_SAMPLE * usb_audio_channel_count);
-    self->output_buffer = m_malloc_without_collect(self->base.max_buffer_length);
-    if (self->output_buffer == NULL) {
-        common_hal_usb_audio_usbspeaker_deinit(self);
-        m_malloc_fail(self->base.max_buffer_length);
-    }
-    memset(self->output_buffer, 0, self->base.max_buffer_length);
-
     self->ring_head = 0;
     self->ring_tail = 0;
     self->ring_count = 0;
@@ -114,32 +104,32 @@ void usb_audio_usbspeaker_background_drain(const uint8_t *in, size_t n) {
     if (self == NULL || n == 0) {
         return;
     }
-    if (n >= self->ring_len) {
+    if (n >= USB_AUDIO_SPEAKER_RING_SIZE) {
         // A single chunk larger than the whole ring can only contribute its
         // newest tail. (Cannot happen with USB packets << ring size, but keep
         // the copies provably in-bounds.)
-        in += n - self->ring_len;
-        n = self->ring_len;
+        in += n - USB_AUDIO_SPEAKER_RING_SIZE;
+        n = USB_AUDIO_SPEAKER_RING_SIZE;
     }
 
     common_hal_mcu_disable_interrupts();
 
-    size_t free_space = self->ring_len - self->ring_count;
+    size_t free_space = USB_AUDIO_SPEAKER_RING_SIZE - self->ring_count;
     if (n > free_space) {
         // Overrun: advance the read cursor past the oldest bytes we're about to
         // overwrite, keeping latency bounded and following the newest host audio.
         size_t drop = n - free_space;
-        self->ring_tail = (self->ring_tail + drop) % self->ring_len;
+        self->ring_tail = (self->ring_tail + drop) % USB_AUDIO_SPEAKER_RING_SIZE;
         self->ring_count -= drop;
     }
 
     // Copy in one or two segments, wrapping at the end of the ring.
-    size_t first = MIN(n, self->ring_len - self->ring_head);
+    size_t first = MIN(n, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_head);
     memcpy(&self->ring[self->ring_head], in, first);
     if (n > first) {
         memcpy(&self->ring[0], in + first, n - first);
     }
-    self->ring_head = (self->ring_head + n) % self->ring_len;
+    self->ring_head = (self->ring_head + n) % USB_AUDIO_SPEAKER_RING_SIZE;
     self->ring_count += n;
 
     common_hal_mcu_enable_interrupts();
@@ -167,12 +157,12 @@ uint32_t common_hal_usb_audio_usbspeaker_read(usb_audio_usbspeaker_obj_t *self,
     // but stay defensive so the returned count is always a whole number).
     to_copy -= to_copy % bytes_per_frame;
 
-    size_t first = MIN(to_copy, self->ring_len - self->ring_tail);
+    size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
     memcpy(buffer, &self->ring[self->ring_tail], first);
     if (to_copy > first) {
         memcpy((uint8_t *)buffer + first, &self->ring[0], to_copy - first);
     }
-    self->ring_tail = (self->ring_tail + to_copy) % self->ring_len;
+    self->ring_tail = (self->ring_tail + to_copy) % USB_AUDIO_SPEAKER_RING_SIZE;
     self->ring_count -= to_copy;
     common_hal_mcu_enable_interrupts();
 
@@ -203,35 +193,56 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
 
     uint32_t half = self->base.max_buffer_length / 2;
     uint8_t *out = self->output_buffer + half * self->output_index;
+    int16_t *word_out = (int16_t *)out;
+    int16_t *word_ring = (int16_t *)self->ring;
     self->output_index = 1 - self->output_index;
 
     // Consumer side of the SPSC ring (runs in the output backend's refill ISR).
     // It is never preempted by the producer, so no interrupt guard is required.
     size_t to_copy = MIN(self->ring_count, (size_t)half);
 
-    size_t first = MIN(to_copy, self->ring_len - self->ring_tail);
-    memcpy(out, &self->ring[self->ring_tail], first);
-    if (to_copy > first) {
-        memcpy(out + first, &self->ring[0], to_copy - first);
+    size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+        memcpy(out, &self->ring[self->ring_tail], first);
+        if (to_copy > first) {
+            memcpy(out + first, &self->ring[0], to_copy - first);
+        }
+    } else {
+        for (size_t i = self->ring_tail / USB_AUDIO_N_BYTES_PER_SAMPLE; i < first / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
+            word_out[i >> 1] = word_ring[i];
+        }
+        if (to_copy > first) {
+            for (size_t i = 0; i < (to_copy - first) / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
+                word_out[(first / USB_AUDIO_N_BYTES_PER_SAMPLE) + (i >> 1)] = word_ring[i];
+            }
+        }
     }
-    self->ring_tail = (self->ring_tail + to_copy) % self->ring_len;
+    self->ring_tail = (self->ring_tail + to_copy) % USB_AUDIO_SPEAKER_RING_SIZE;
     self->ring_count -= to_copy;
 
     if (to_copy < half) {
         // Underrun: pad the remainder with silence. Samples are signed, so
         // silence is 0. This is the consume-side of the pacing failure mode
         // tracked in the usb-audio-artifact-pacing memory: we never spin.
-        memset(out + to_copy, 0, half - to_copy);
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+            memset(out + to_copy, 0, half - to_copy);
+        } else {
+            memset(out + (to_copy >> 1), 0, (half - to_copy) >> 1);
+        }
     }
 
-    // Mono only for v1, so the single-channel offset is always 0; computed the
-    // same way as audiocore.RawSample so stereo (interleaved ring) can extend it.
+    // Computed the same way as audiocore.RawSample so stereo (interleaved ring)
+    // can extend it.
     if (single_channel_output) {
         out += (channel % self->base.channel_count) * (self->base.bits_per_sample / 8);
     }
 
     *buffer = out;
-    *buffer_length = half;
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+        *buffer_length = half;
+    } else {
+        *buffer_length = half >> 1;
+    }
     // A live USB stream is infinite; never report DONE or the backend would stop.
     return GET_BUFFER_MORE_DATA;
 }
diff --git a/shared-module/usb_audio/USBSpeaker.h b/shared-module/usb_audio/USBSpeaker.h
index d1694cd4745..8c06cff519d 100644
--- a/shared-module/usb_audio/USBSpeaker.h
+++ b/shared-module/usb_audio/USBSpeaker.h
@@ -25,6 +25,11 @@
 // Bytes per audio frame in the negotiated UAC2 format (mono 16-bit for v1).
 #define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_N_BYTES_PER_SAMPLE * USB_AUDIO_N_CHANNELS)
 
+// Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
+// audiocore.RawSample's convention where base.max_buffer_length is the whole
+// buffer and get_buffer() returns half of it.
+#define USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE (2 * USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER * USB_AUDIO_SPEAKER_BYTES_PER_FRAME)
+
 // Host -> board receive ring size. Mirrors CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ
 // (16 * the full-speed OUT wMaxPacketSize) but is spelled out from the format
 // constants so this struct definition stays free of the TinyUSB headers. A
@@ -46,7 +51,7 @@ typedef struct usb_audio_usbspeaker_obj {
     size_t ring_count;  // valid bytes currently in the ring
 
     // Owned double-buffer returned to the output backend by get_buffer().
-    uint8_t *output_buffer;
+    uint8_t output_buffer[USB_AUDIO_SPEAKER_OUTPUT_BUFFER_SIZE];
     uint8_t output_index;  // 0 or 1: which half get_buffer() fills next
 } usb_audio_usbspeaker_obj_t;
 
diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index add1ec1c972..9d3a244af8e 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -39,15 +39,14 @@ static uint8_t usb_audio_spk_as_itf = 0xff;
 
 uint32_t usb_audio_sample_rate;
 uint8_t usb_audio_channel_count;
-uint8_t usb_audio_bits_per_sample;
 bool usb_audio_microphone_enabled;
 bool usb_audio_speaker_enabled;
 
 // Audio control state surfaced to the host. One extra entry for the master channel 0.
-static int8_t usb_audio_mute[USB_AUDIO_MAX_CHANNELS + 1];
-static int16_t usb_audio_volume[USB_AUDIO_MAX_CHANNELS + 1];
+static int8_t usb_audio_mute[USB_AUDIO_N_CHANNELS + 1];
+static int16_t usb_audio_volume[USB_AUDIO_N_CHANNELS + 1];
 
-bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, mp_int_t bits_per_sample, bool microphone, bool speaker) {
+bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, bool microphone, bool speaker) {
     if (tud_connected()) {
         return false;
     }
@@ -64,7 +63,6 @@ bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count
 
     usb_audio_sample_rate = sample_rate;
     usb_audio_channel_count = channel_count;
-    usb_audio_bits_per_sample = bits_per_sample;
     usb_audio_microphone_enabled = microphone;
     usb_audio_speaker_enabled = speaker;
     usb_audio_is_enabled = true;
@@ -147,7 +145,7 @@ void usb_audio_setup_singletons(void) {
 // terminal roles reverse: the input terminal is the USB-streaming side and the
 // output terminal is the desktop speaker, and the AS interface links the input
 // terminal (0x01). Async feedback for true clock matching is a later step.
-#define USB_AUDIO_SPEAKER_ONE_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
+#define USB_AUDIO_SPEAKER_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
     /* Standard Interface Association Descriptor (IAD) */ \
     TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
     /* Standard AC Interface Descriptor(4.7.1) */ \
@@ -157,35 +155,7 @@ void usb_audio_setup_singletons(void) {
     /* Clock Source Descriptor(4.7.2.1) */ \
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
-    /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
-    TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
-    /* Feature Unit Descriptor(4.7.2.8) */ \
-    TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
-    /* Standard AS Interface Descriptor(4.9.1) -- alt 0, zero bandwidth */ \
-    TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00), \
-    /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
-    TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
-    /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
-    /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
-    TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
-    /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t)((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
-    /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
-    TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
-
-#define USB_AUDIO_SPEAKER_TWO_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epsize) \
-    /* Standard Interface Association Descriptor (IAD) */ \
-    TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
-    /* Standard AC Interface Descriptor(4.7.1) */ \
-    TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
-    /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
-    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_DESKTOP_SPEAKER, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
-    /* Clock Source Descriptor(4.7.2.1) */ \
-    TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
-    /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -195,7 +165,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -208,37 +178,7 @@ void usb_audio_setup_singletons(void) {
 // (lib/tinyusb/src/device/usbd.h) but drops the trailing feedback endpoint, so
 // the streaming alt-setting declares a single IN endpoint (_nEPs = 0x00). Async
 // feedback for true clock matching is a later step.
-#define USB_AUDIO_MIC_ONE_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
-  /* Standard Interface Association Descriptor (IAD) */ \
-  TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
-  /* Standard AC Interface Descriptor(4.7.1) */ \
-  TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
-  /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
-  TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_MICROPHONE, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
-  /* Clock Source Descriptor(4.7.2.1) */ \
-  TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
-  /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
-  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
-  /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
-  TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
-  /* Feature Unit Descriptor(4.7.2.8) */ \
-  TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
-  /* Standard AS Interface Descriptor(4.9.1) */ \
-  /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */ \
-  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
-  /* Standard AS Interface Descriptor(4.9.1) */ \
-  /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
-  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
-  /* Class-Specific AS Interface Descriptor(4.9.2) */ \
-  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
-  /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
-  TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
-  /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
-  TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
-  /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
-  TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
-
-#define USB_AUDIO_MIC_TWO_CH_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
+#define USB_AUDIO_MIC_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
   /* Standard Interface Association Descriptor (IAD) */ \
   TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
   /* Standard AC Interface Descriptor(4.7.1) */ \
@@ -248,7 +188,7 @@ void usb_audio_setup_singletons(void) {
   /* Clock Source Descriptor(4.7.2.1) */ \
   TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
   /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
-  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
   /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
   TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
   /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -260,7 +200,7 @@ void usb_audio_setup_singletons(void) {
   /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
   TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
   /* Class-Specific AS Interface Descriptor(4.9.2) */ \
-  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
   /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
   TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
   /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -268,7 +208,7 @@ void usb_audio_setup_singletons(void) {
   /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
   TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
 
-// Hand-rolled UAC2 mono headset (microphone + speaker both enabled): one audio function
+// Hand-rolled UAC2 headset (microphone + speaker both enabled): one audio function
 // presenting both a speaker (host -> board OUT) and a microphone (board -> host
 // IN) at once. This combines USB_AUDIO_SPEAKER_DESCRIPTOR's speaker chain with
 // USB_AUDIO_MIC_DESCRIPTOR's mic chain under a single IAD. The two chains
@@ -284,21 +224,21 @@ void usb_audio_setup_singletons(void) {
     /* Standard AC Interface Descriptor(4.7.1) */ \
     TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
     /* Class-Specific AC Interface Header Descriptor(4.7.2) -- clock + both chains */ \
-    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_HEADSET, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + 2 * (TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN), /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+    TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_HEADSET, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + 2 * (TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN), /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
     /* Clock Source Descriptor(4.7.2.1) -- shared by both chains */ \
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ 0x00, /*_stridx*/ 0x00), \
     /* --- Speaker chain (host -> board) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
-    TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x00, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* --- Mic chain (board -> host) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- generic microphone */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
-    TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- USB streaming out to the host */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* --- Speaker AudioStreaming interface (_itfnum + 1) --- */ \
@@ -307,7 +247,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the speaker input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -320,7 +260,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one IN endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 2), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the mic output terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -344,17 +284,9 @@ size_t usb_audio_descriptor_length(void) {
         return USB_AUDIO_HEADSET_DESC_LEN;
     }
     if (usb_audio_direction_is_output()) {
-        if (usb_audio_channel_count == 1) {
-            return USB_AUDIO_SPEAKER_ONE_CH_DESC_LEN;
-        } else {
-            return USB_AUDIO_SPEAKER_TWO_CH_DESC_LEN;
-        }
-    }
-    if (usb_audio_channel_count == 1) {
-        return USB_AUDIO_MIC_ONE_CH_DESC_LEN;
-    } else {
-        return USB_AUDIO_MIC_TWO_CH_DESC_LEN;
+        return USB_AUDIO_SPEAKER_DESC_LEN;
     }
+    return USB_AUDIO_MIC_DESC_LEN;
 }
 
 size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *descriptor_counts, uint8_t *current_interface_string) {
@@ -400,11 +332,11 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
 
         (*current_interface_string)++;
         // One IAD wrapping an AudioControl + two AudioStreaming interfaces, plus
-        // one OUT and one IN endpoint.
+        // two OUT and two IN endpoints.
         descriptor_counts->current_interface += 3;
-        descriptor_counts->num_out_endpoints++;
-        descriptor_counts->num_in_endpoints++;
-        descriptor_counts->current_endpoint += 2;
+        descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS * 2;
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
@@ -417,103 +349,55 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         // The AudioStreaming interface follows the AudioControl interface.
         usb_audio_spk_as_itf = descriptor_counts->current_interface + 1;
 
-        if (usb_audio_channel_count == 1) {
-            const uint8_t usb_audio_descriptor[] = {
-                USB_AUDIO_SPEAKER_ONE_CH_DESCRIPTOR(
-                    /*_itfnum*/ descriptor_counts->current_interface,
-                    /*_stridx*/ *current_interface_string,
-                    /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
-                    /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-                    /*_epout*/ iso_ep_num,
-                    /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
-            };
-
-            (*current_interface_string)++;
-            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one OUT endpoint.
-            descriptor_counts->current_interface += 2;
-            if (!forced_iso_ep) {
-                descriptor_counts->num_out_endpoints++;
-                descriptor_counts->current_endpoint++;
-            }
-
-            memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
-
-            return sizeof(usb_audio_descriptor);
-        } else {
-            const uint8_t usb_audio_descriptor[] = {
-                USB_AUDIO_SPEAKER_TWO_CH_DESCRIPTOR(
-                    /*_itfnum*/ descriptor_counts->current_interface,
-                    /*_stridx*/ *current_interface_string,
-                    /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
-                    /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-                    /*_epout*/ iso_ep_num,
-                    /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
-            };
-
-            (*current_interface_string)++;
-            // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two OUT endpoints.
-            descriptor_counts->current_interface += 2;
-            if (!forced_iso_ep) {
-                descriptor_counts->num_out_endpoints += 2;
-                descriptor_counts->current_endpoint += 2;
-            }
-
-            memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
-
-            return sizeof(usb_audio_descriptor);
-        }
-    }
-
-    usb_add_interface_string(*current_interface_string, "CircuitPython Microphone");
-
-    // The AudioStreaming interface follows the AudioControl interface.
-    usb_audio_mic_as_itf = descriptor_counts->current_interface + 1;
-
-    if (usb_audio_channel_count == 1) {
         const uint8_t usb_audio_descriptor[] = {
-            USB_AUDIO_MIC_ONE_CH_DESCRIPTOR(
+            USB_AUDIO_SPEAKER_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
                 /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-                /*_epin*/ iso_ep_num | 0x80,
-                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
+                /*_epout*/ iso_ep_num,
+                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
         };
 
         (*current_interface_string)++;
-        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus one IN endpoint.
+        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two OUT endpoints.
         descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
-            descriptor_counts->num_in_endpoints++;
-            descriptor_counts->current_endpoint++;
+            descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
+            descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
         }
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
         return sizeof(usb_audio_descriptor);
-    } else {
-        const uint8_t usb_audio_descriptor[] = {
-            USB_AUDIO_MIC_TWO_CH_DESCRIPTOR(
-                /*_itfnum*/ descriptor_counts->current_interface,
-                /*_stridx*/ *current_interface_string,
-                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
-                /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
-                /*_epin*/ iso_ep_num | 0x80,
-                /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
-        };
+    }
 
-        (*current_interface_string)++;
-        // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two IN endpoints.
-        descriptor_counts->current_interface += 2;
-        if (!forced_iso_ep) {
-            descriptor_counts->num_in_endpoints += 2;
-            descriptor_counts->current_endpoint += 2;
-        }
+    usb_add_interface_string(*current_interface_string, "CircuitPython Microphone");
 
-        memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
+    // The AudioStreaming interface follows the AudioControl interface.
+    usb_audio_mic_as_itf = descriptor_counts->current_interface + 1;
 
-        return sizeof(usb_audio_descriptor);
+    const uint8_t usb_audio_descriptor[] = {
+        USB_AUDIO_MIC_DESCRIPTOR(
+            /*_itfnum*/ descriptor_counts->current_interface,
+            /*_stridx*/ *current_interface_string,
+            /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+            /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
+            /*_epin*/ iso_ep_num | 0x80,
+            /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
+    };
+
+    (*current_interface_string)++;
+    // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two IN endpoints.
+    descriptor_counts->current_interface += 2;
+    if (!forced_iso_ep) {
+        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
     }
+
+    memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
+
+    return sizeof(usb_audio_descriptor);
 }
 
 // --------------------------------------------------------------------+
@@ -660,7 +544,7 @@ bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Mute/volume state is shared across them.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
+        if (channelNum > USB_AUDIO_N_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
@@ -711,7 +595,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Feature unit (mute/volume) for either the speaker or mic chain.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
+        if (channelNum > USB_AUDIO_N_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
diff --git a/shared-module/usb_audio/__init__.h b/shared-module/usb_audio/__init__.h
index 8ec13f90853..5730e6ef60b 100644
--- a/shared-module/usb_audio/__init__.h
+++ b/shared-module/usb_audio/__init__.h
@@ -17,7 +17,7 @@
 // called before USB is connected (i.e. from boot.py); they return false
 // otherwise. At least one of microphone/speaker must be true; enabling both
 // presents a combined headset.
-bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, mp_int_t bits_per_sample, bool microphone, bool speaker);
+bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, bool microphone, bool speaker);
 bool shared_module_usb_audio_disable(void);
 
 // True once enable() has been called successfully.
@@ -36,7 +36,6 @@ bool usb_audio_speaker_streaming(void);
 // Negotiated audio format, valid when usb_audio_enabled() is true.
 extern uint32_t usb_audio_sample_rate;
 extern uint8_t usb_audio_channel_count;
-extern uint8_t usb_audio_bits_per_sample;
 
 // Which streams were requested in enable(), valid when usb_audio_enabled() is
 // true. Both true presents a combined headset.
diff --git a/shared-module/usb_audio/usb_audio_descriptors.h b/shared-module/usb_audio/usb_audio_descriptors.h
index d94c8acabdf..597a78ab82c 100644
--- a/shared-module/usb_audio/usb_audio_descriptors.h
+++ b/shared-module/usb_audio/usb_audio_descriptors.h
@@ -27,10 +27,10 @@ size_t usb_audio_descriptor_length(void);
 // The isochronous IN endpoint's wMaxPacketSize in the USB descriptor is computed
 // for this rate, so it is the highest rate usb_audio.enable() will accept.
 #define USB_AUDIO_MAX_SAMPLE_RATE (48000)
-#define USB_AUDIO_MAX_CHANNELS (2)
 
-// 16-bit signed LE PCM.
+// 16-bit signed LE stereo PCM.
 #define USB_AUDIO_N_BYTES_PER_SAMPLE (2)
+#define USB_AUDIO_N_CHANNELS (2)
 #define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_N_BYTES_PER_SAMPLE * 8)
 
 // Endpoint number for the single isochronous audio data endpoint. Most device
@@ -76,23 +76,7 @@ size_t usb_audio_descriptor_length(void);
 // These TUD_AUDIO_DESC_*_LEN macros come from TinyUSB's usbd.h; this expression
 // is only expanded where that header is already included (never at the point
 // tusb_config.h includes us), so the header stays dependency-free.
-#define USB_AUDIO_SPEAKER_ONE_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
-    + TUD_AUDIO_DESC_STD_AC_LEN \
-    + TUD_AUDIO_DESC_CS_AC_LEN \
-    + TUD_AUDIO_DESC_CLK_SRC_LEN \
-    /* speaker chain: USB-streaming input terminal -> feature unit -> speaker */ \
-    + TUD_AUDIO_DESC_INPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
-    /* speaker AudioStreaming interface (alt 0 + alt 1 with OUT endpoint) */ \
-    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
-    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
-    + TUD_AUDIO_DESC_CS_AS_INT_LEN \
-    + TUD_AUDIO_DESC_TYPE_I_FORMAT_LEN \
-    + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
-    + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
-
-#define USB_AUDIO_SPEAKER_TWO_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+#define USB_AUDIO_SPEAKER_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
     + TUD_AUDIO_DESC_STD_AC_LEN \
     + TUD_AUDIO_DESC_CS_AC_LEN \
     + TUD_AUDIO_DESC_CLK_SRC_LEN \
@@ -108,23 +92,7 @@ size_t usb_audio_descriptor_length(void);
     + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
     + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
 
-#define USB_AUDIO_MIC_ONE_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
-    + TUD_AUDIO_DESC_STD_AC_LEN \
-    + TUD_AUDIO_DESC_CS_AC_LEN \
-    + TUD_AUDIO_DESC_CLK_SRC_LEN \
-    /* mic chain: microphone input terminal -> feature unit -> USB-streaming out */ \
-    + TUD_AUDIO_DESC_INPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
-    /* mic AudioStreaming interface (alt 0 + alt 1 with IN endpoint) */ \
-    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
-    + TUD_AUDIO_DESC_STD_AS_INT_LEN \
-    + TUD_AUDIO_DESC_CS_AS_INT_LEN \
-    + TUD_AUDIO_DESC_TYPE_I_FORMAT_LEN \
-    + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN \
-    + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
-
-#define USB_AUDIO_MIC_TWO_CH_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
+#define USB_AUDIO_MIC_DESC_LEN (TUD_AUDIO_DESC_IAD_LEN \
     + TUD_AUDIO_DESC_STD_AC_LEN \
     + TUD_AUDIO_DESC_CS_AC_LEN \
     + TUD_AUDIO_DESC_CLK_SRC_LEN \
@@ -155,11 +123,11 @@ size_t usb_audio_descriptor_length(void);
     + TUD_AUDIO_DESC_CLK_SRC_LEN \
     /* speaker chain: USB-streaming input terminal -> feature unit -> speaker */ \
     + TUD_AUDIO_DESC_INPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
+    + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN \
     + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
     /* mic chain: microphone input terminal -> feature unit -> USB-streaming out */ \
     + TUD_AUDIO_DESC_INPUT_TERM_LEN \
-    + TUD_AUDIO_DESC_FEATURE_UNIT_ONE_CHANNEL_LEN \
+    + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN \
     + TUD_AUDIO_DESC_OUTPUT_TERM_LEN \
     /* speaker AudioStreaming interface (alt 0 + alt 1 with OUT endpoint) */ \
     + TUD_AUDIO_DESC_STD_AS_INT_LEN \
diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
index 12f32988bc2..a10cd712226 100644
--- a/supervisor/shared/usb/tusb_config.h
+++ b/supervisor/shared/usb/tusb_config.h
@@ -142,9 +142,9 @@ extern "C" {
 
 #define CFG_TUD_AUDIO_ENABLE_EP_IN                  1
 #define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_MAX_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_N_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
 // Deep software FIFO so the 1 ms refill keeps clear of the underrun floor.
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ        (16 * CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
 
@@ -154,9 +154,9 @@ extern "C" {
 // IN sizing above.
 #define CFG_TUD_AUDIO_ENABLE_EP_OUT                 1
 #define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_MAX_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_N_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
 // Deep software FIFO so the 1 ms drain keeps clear of the overrun ceiling.
 #define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ       (16 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
 #endif

From b26ef7d3ab67fcbd9978d077828ee6177a14dfd3 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Tue, 7 Jul 2026 22:43:29 -0500
Subject: [PATCH 07/11] Rename audio constants

---
 shared-bindings/usb_audio/__init__.c          |  2 +-
 shared-module/usb_audio/USBMicrophone.c       |  4 +-
 shared-module/usb_audio/USBSpeaker.c          | 12 ++---
 shared-module/usb_audio/USBSpeaker.h          |  4 +-
 shared-module/usb_audio/__init__.c            | 46 +++++++++----------
 .../usb_audio/usb_audio_descriptors.h         |  8 ++--
 6 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 00ec82f10ae..7bf20807f3e 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -112,7 +112,7 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     mp_int_t sample_rate = mp_arg_validate_int_range(args[ARG_sample_rate].u_int, 1, USB_AUDIO_MAX_SAMPLE_RATE, MP_QSTR_sample_rate);
-    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_N_CHANNELS, MP_QSTR_channel_count);
+    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_MAX_CHANNELS, MP_QSTR_channel_count);
     bool microphone = args[ARG_microphone].u_bool;
     bool speaker = args[ARG_speaker].u_bool;
 
diff --git a/shared-module/usb_audio/USBMicrophone.c b/shared-module/usb_audio/USBMicrophone.c
index a1228ad1c64..c10258477c2 100644
--- a/shared-module/usb_audio/USBMicrophone.c
+++ b/shared-module/usb_audio/USBMicrophone.c
@@ -140,14 +140,14 @@ size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
         }
 
         size_t n;
-        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
             n = MIN(self->buffer_length, max_bytes - filled);
             memcpy(out + filled, self->buffer, n);
         } else {
             n = MIN(self->buffer_length << 1, max_bytes - filled);
             int16_t *word_buffer = (int16_t *)self->buffer;
             int16_t *word_out = (int16_t *)(out + filled);
-            for (size_t i = 0; i < n / USB_AUDIO_N_BYTES_PER_SAMPLE; i++) {
+            for (size_t i = 0; i < n / USB_AUDIO_BYTES_PER_SAMPLE; i++) {
                 word_out[i] = word_buffer[i >> 1];
             }
         }
diff --git a/shared-module/usb_audio/USBSpeaker.c b/shared-module/usb_audio/USBSpeaker.c
index 310eb3cd7d2..e2f2bf4f525 100644
--- a/shared-module/usb_audio/USBSpeaker.c
+++ b/shared-module/usb_audio/USBSpeaker.c
@@ -202,18 +202,18 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
     size_t to_copy = MIN(self->ring_count, (size_t)half);
 
     size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
-    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
         memcpy(out, &self->ring[self->ring_tail], first);
         if (to_copy > first) {
             memcpy(out + first, &self->ring[0], to_copy - first);
         }
     } else {
-        for (size_t i = self->ring_tail / USB_AUDIO_N_BYTES_PER_SAMPLE; i < first / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
+        for (size_t i = self->ring_tail / USB_AUDIO_BYTES_PER_SAMPLE; i < first / USB_AUDIO_BYTES_PER_SAMPLE; i += 2) {
             word_out[i >> 1] = word_ring[i];
         }
         if (to_copy > first) {
-            for (size_t i = 0; i < (to_copy - first) / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
-                word_out[(first / USB_AUDIO_N_BYTES_PER_SAMPLE) + (i >> 1)] = word_ring[i];
+            for (size_t i = 0; i < (to_copy - first) / USB_AUDIO_BYTES_PER_SAMPLE; i += 2) {
+                word_out[(first / USB_AUDIO_BYTES_PER_SAMPLE) + (i >> 1)] = word_ring[i];
             }
         }
     }
@@ -224,7 +224,7 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
         // Underrun: pad the remainder with silence. Samples are signed, so
         // silence is 0. This is the consume-side of the pacing failure mode
         // tracked in the usb-audio-artifact-pacing memory: we never spin.
-        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
             memset(out + to_copy, 0, half - to_copy);
         } else {
             memset(out + (to_copy >> 1), 0, (half - to_copy) >> 1);
@@ -238,7 +238,7 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
     }
 
     *buffer = out;
-    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
         *buffer_length = half;
     } else {
         *buffer_length = half >> 1;
diff --git a/shared-module/usb_audio/USBSpeaker.h b/shared-module/usb_audio/USBSpeaker.h
index 8c06cff519d..27007ad275d 100644
--- a/shared-module/usb_audio/USBSpeaker.h
+++ b/shared-module/usb_audio/USBSpeaker.h
@@ -22,8 +22,8 @@
 // comfortably inside the ring.
 #define USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER (128)
 
-// Bytes per audio frame in the negotiated UAC2 format (mono 16-bit for v1).
-#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_N_BYTES_PER_SAMPLE * USB_AUDIO_N_CHANNELS)
+// Bytes per audio frame in the negotiated UAC2 format (stereo 16-bit).
+#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_BYTES_PER_SAMPLE * USB_AUDIO_MAX_CHANNELS)
 
 // Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
 // audiocore.RawSample's convention where base.max_buffer_length is the whole
diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index 9d3a244af8e..10bc368616a 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -43,8 +43,8 @@ bool usb_audio_microphone_enabled;
 bool usb_audio_speaker_enabled;
 
 // Audio control state surfaced to the host. One extra entry for the master channel 0.
-static int8_t usb_audio_mute[USB_AUDIO_N_CHANNELS + 1];
-static int16_t usb_audio_volume[USB_AUDIO_N_CHANNELS + 1];
+static int8_t usb_audio_mute[USB_AUDIO_MAX_CHANNELS + 1];
+static int16_t usb_audio_volume[USB_AUDIO_MAX_CHANNELS + 1];
 
 bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, bool microphone, bool speaker) {
     if (tud_connected()) {
@@ -53,7 +53,7 @@ bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count
 
     // One scratch chunk (1 ms at the sample rate); we loop until the FIFO reaches
     // the setpoint.
-    usb_audio_mic_samples_len = sample_rate / 1000 * channel_count * USB_AUDIO_N_BYTES_PER_SAMPLE;
+    usb_audio_mic_samples_len = sample_rate / 1000 * channel_count * USB_AUDIO_BYTES_PER_SAMPLE;
     usb_audio_mic_samples = (int16_t *)m_malloc_without_collect(usb_audio_mic_samples_len);
     if (usb_audio_mic_samples == NULL) {
         m_malloc_fail(usb_audio_mic_samples_len);
@@ -155,7 +155,7 @@ void usb_audio_setup_singletons(void) {
     /* Clock Source Descriptor(4.7.2.1) */ \
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -165,7 +165,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -188,7 +188,7 @@ void usb_audio_setup_singletons(void) {
   /* Clock Source Descriptor(4.7.2.1) */ \
   TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
   /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
-  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
   /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
   TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
   /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -200,7 +200,7 @@ void usb_audio_setup_singletons(void) {
   /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
   TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
   /* Class-Specific AS Interface Descriptor(4.9.2) */ \
-  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
   /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
   TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
   /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -229,14 +229,14 @@ void usb_audio_setup_singletons(void) {
     TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ 0x00, /*_stridx*/ 0x00), \
     /* --- Speaker chain (host -> board) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x00, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* --- Mic chain (board -> host) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- generic microphone */ \
-    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- USB streaming out to the host */ \
@@ -247,7 +247,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the speaker input terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -260,7 +260,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one IN endpoint */ \
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 2), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the mic output terminal */ \
-    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -319,7 +319,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
             USB_AUDIO_HEADSET_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
-                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+                /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
                 /*_epout*/ ep_out,
                 /*_epin*/ ep_in | 0x80,
@@ -334,9 +334,9 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         // One IAD wrapping an AudioControl + two AudioStreaming interfaces, plus
         // two OUT and two IN endpoints.
         descriptor_counts->current_interface += 3;
-        descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
-        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
-        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS * 2;
+        descriptor_counts->num_out_endpoints += USB_AUDIO_MAX_CHANNELS;
+        descriptor_counts->num_in_endpoints += USB_AUDIO_MAX_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS * 2;
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
@@ -353,7 +353,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
             USB_AUDIO_SPEAKER_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
-                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+                /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
                 /*_epout*/ iso_ep_num,
                 /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
@@ -363,8 +363,8 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two OUT endpoints.
         descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
-            descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
-            descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
+            descriptor_counts->num_out_endpoints += USB_AUDIO_MAX_CHANNELS;
+            descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS;
         }
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
@@ -381,7 +381,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         USB_AUDIO_MIC_DESCRIPTOR(
             /*_itfnum*/ descriptor_counts->current_interface,
             /*_stridx*/ *current_interface_string,
-            /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
+            /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
             /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
             /*_epin*/ iso_ep_num | 0x80,
             /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
@@ -391,8 +391,8 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
     // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two IN endpoints.
     descriptor_counts->current_interface += 2;
     if (!forced_iso_ep) {
-        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
-        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->num_in_endpoints += USB_AUDIO_MAX_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS;
     }
 
     memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
@@ -544,7 +544,7 @@ bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Mute/volume state is shared across them.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_N_CHANNELS) {
+        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
@@ -595,7 +595,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Feature unit (mute/volume) for either the speaker or mic chain.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_N_CHANNELS) {
+        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
diff --git a/shared-module/usb_audio/usb_audio_descriptors.h b/shared-module/usb_audio/usb_audio_descriptors.h
index 597a78ab82c..a6622c8f8eb 100644
--- a/shared-module/usb_audio/usb_audio_descriptors.h
+++ b/shared-module/usb_audio/usb_audio_descriptors.h
@@ -27,11 +27,11 @@ size_t usb_audio_descriptor_length(void);
 // The isochronous IN endpoint's wMaxPacketSize in the USB descriptor is computed
 // for this rate, so it is the highest rate usb_audio.enable() will accept.
 #define USB_AUDIO_MAX_SAMPLE_RATE (48000)
+#define USB_AUDIO_MAX_CHANNELS (2)
 
-// 16-bit signed LE stereo PCM.
-#define USB_AUDIO_N_BYTES_PER_SAMPLE (2)
-#define USB_AUDIO_N_CHANNELS (2)
-#define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_N_BYTES_PER_SAMPLE * 8)
+// 16-bit signed LE PCM.
+#define USB_AUDIO_BYTES_PER_SAMPLE (2)
+#define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_BYTES_PER_SAMPLE * 8)
 
 // Endpoint number for the single isochronous audio data endpoint. Most device
 // controllers accept an ISO endpoint on any number, so the descriptor builder

From 3a2934f42b9a368ac742c6dd17bbd07983d91063 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Wed, 8 Jul 2026 08:36:02 -0500
Subject: [PATCH 08/11] Fix CFG_TUD_AUDIO constants

---
 supervisor/shared/usb/tusb_config.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
index a10cd712226..5530f751d1c 100644
--- a/supervisor/shared/usb/tusb_config.h
+++ b/supervisor/shared/usb/tusb_config.h
@@ -141,10 +141,10 @@ extern "C" {
 #define CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ            64
 
 #define CFG_TUD_AUDIO_ENABLE_EP_IN                  1
-#define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_N_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX  USB_AUDIO_BYTES_PER_SAMPLE
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX          USB_AUDIO_MAX_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
 // Deep software FIFO so the 1 ms refill keeps clear of the underrun floor.
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ        (16 * CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
 
@@ -153,10 +153,10 @@ extern "C" {
 // descriptor (still mic-only until the speaker descriptor lands). Mirrors the
 // IN sizing above.
 #define CFG_TUD_AUDIO_ENABLE_EP_OUT                 1
-#define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX  USB_AUDIO_N_BYTES_PER_SAMPLE
-#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_N_CHANNELS
+#define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX  USB_AUDIO_BYTES_PER_SAMPLE
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX          USB_AUDIO_MAX_CHANNELS
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
 // Deep software FIFO so the 1 ms drain keeps clear of the overrun ceiling.
 #define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ       (16 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
 #endif

From f17c5d9ab8a4f5291dd25dd8404f5d5903ac6c84 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Wed, 8 Jul 2026 09:37:41 -0500
Subject: [PATCH 09/11] Improve mono to stereo conversion on USBMicrophone

---
 shared-module/usb_audio/USBMicrophone.c | 28 +++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/shared-module/usb_audio/USBMicrophone.c b/shared-module/usb_audio/USBMicrophone.c
index c10258477c2..172ef5465e3 100644
--- a/shared-module/usb_audio/USBMicrophone.c
+++ b/shared-module/usb_audio/USBMicrophone.c
@@ -102,6 +102,24 @@ bool common_hal_usb_audio_usbmicrophone_get_paused(usb_audio_usbmicrophone_obj_t
     return self->playing && self->paused;
 }
 
+static inline uint32_t copy16lsb(uint32_t val) {
+    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    return __PKHBT(val, val, 16);
+    #else
+    val &= 0x0000ffff;
+    return val | (val << 16);
+    #endif
+}
+
+static inline uint32_t copy16msb(uint32_t val) {
+    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    return __PKHTB(val, val, 16);
+    #else
+    val &= 0xffff0000;
+    return val | (val >> 16);
+    #endif
+}
+
 size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
     usb_audio_usbmicrophone_obj_t *self = active_microphone;
     if (self == NULL || !self->playing || self->paused || self->sample == MP_OBJ_NULL) {
@@ -145,10 +163,12 @@ size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
             memcpy(out + filled, self->buffer, n);
         } else {
             n = MIN(self->buffer_length << 1, max_bytes - filled);
-            int16_t *word_buffer = (int16_t *)self->buffer;
-            int16_t *word_out = (int16_t *)(out + filled);
-            for (size_t i = 0; i < n / USB_AUDIO_BYTES_PER_SAMPLE; i++) {
-                word_out[i] = word_buffer[i >> 1];
+            uint32_t *word_buffer = (uint32_t *)self->buffer;
+            uint32_t *word_out = (uint32_t *)(out + filled);
+            for (size_t i = 0; i < n / sizeof(uint32_t); i += 2) {
+                uint32_t v = word_buffer[i >> 1];
+                word_out[i] = copy16lsb(v);
+                word_out[i + 1] = copy16msb(v);
             }
         }
         self->buffer += n;

From 234461b8ce9ec1364e9bdf91d606bee87f9d7b82 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Mon, 13 Jul 2026 11:18:30 -0500
Subject: [PATCH 10/11] Revert rename audio constants

---
 shared-bindings/usb_audio/__init__.c          |  2 +-
 shared-module/usb_audio/USBMicrophone.c       |  2 +-
 shared-module/usb_audio/USBSpeaker.c          | 12 ++---
 shared-module/usb_audio/USBSpeaker.h          |  2 +-
 shared-module/usb_audio/__init__.c            | 48 +++++++++----------
 .../usb_audio/usb_audio_descriptors.h         |  6 +--
 supervisor/shared/usb/tusb_config.h           |  4 +-
 7 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/shared-bindings/usb_audio/__init__.c b/shared-bindings/usb_audio/__init__.c
index 7bf20807f3e..00ec82f10ae 100644
--- a/shared-bindings/usb_audio/__init__.c
+++ b/shared-bindings/usb_audio/__init__.c
@@ -112,7 +112,7 @@ static mp_obj_t usb_audio_enable(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     mp_int_t sample_rate = mp_arg_validate_int_range(args[ARG_sample_rate].u_int, 1, USB_AUDIO_MAX_SAMPLE_RATE, MP_QSTR_sample_rate);
-    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_MAX_CHANNELS, MP_QSTR_channel_count);
+    mp_int_t channel_count = mp_arg_validate_int_range(args[ARG_channel_count].u_int, 1, USB_AUDIO_N_CHANNELS, MP_QSTR_channel_count);
     bool microphone = args[ARG_microphone].u_bool;
     bool speaker = args[ARG_speaker].u_bool;
 
diff --git a/shared-module/usb_audio/USBMicrophone.c b/shared-module/usb_audio/USBMicrophone.c
index 172ef5465e3..9d2a46b7985 100644
--- a/shared-module/usb_audio/USBMicrophone.c
+++ b/shared-module/usb_audio/USBMicrophone.c
@@ -158,7 +158,7 @@ size_t usb_audio_usbmicrophone_background_fill(uint8_t *out, size_t max_bytes) {
         }
 
         size_t n;
-        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
             n = MIN(self->buffer_length, max_bytes - filled);
             memcpy(out + filled, self->buffer, n);
         } else {
diff --git a/shared-module/usb_audio/USBSpeaker.c b/shared-module/usb_audio/USBSpeaker.c
index e2f2bf4f525..310eb3cd7d2 100644
--- a/shared-module/usb_audio/USBSpeaker.c
+++ b/shared-module/usb_audio/USBSpeaker.c
@@ -202,18 +202,18 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
     size_t to_copy = MIN(self->ring_count, (size_t)half);
 
     size_t first = MIN(to_copy, USB_AUDIO_SPEAKER_RING_SIZE - self->ring_tail);
-    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
         memcpy(out, &self->ring[self->ring_tail], first);
         if (to_copy > first) {
             memcpy(out + first, &self->ring[0], to_copy - first);
         }
     } else {
-        for (size_t i = self->ring_tail / USB_AUDIO_BYTES_PER_SAMPLE; i < first / USB_AUDIO_BYTES_PER_SAMPLE; i += 2) {
+        for (size_t i = self->ring_tail / USB_AUDIO_N_BYTES_PER_SAMPLE; i < first / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
             word_out[i >> 1] = word_ring[i];
         }
         if (to_copy > first) {
-            for (size_t i = 0; i < (to_copy - first) / USB_AUDIO_BYTES_PER_SAMPLE; i += 2) {
-                word_out[(first / USB_AUDIO_BYTES_PER_SAMPLE) + (i >> 1)] = word_ring[i];
+            for (size_t i = 0; i < (to_copy - first) / USB_AUDIO_N_BYTES_PER_SAMPLE; i += 2) {
+                word_out[(first / USB_AUDIO_N_BYTES_PER_SAMPLE) + (i >> 1)] = word_ring[i];
             }
         }
     }
@@ -224,7 +224,7 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
         // Underrun: pad the remainder with silence. Samples are signed, so
         // silence is 0. This is the consume-side of the pacing failure mode
         // tracked in the usb-audio-artifact-pacing memory: we never spin.
-        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
+        if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
             memset(out + to_copy, 0, half - to_copy);
         } else {
             memset(out + (to_copy >> 1), 0, (half - to_copy) >> 1);
@@ -238,7 +238,7 @@ audioio_get_buffer_result_t usb_audio_usbspeaker_get_buffer(usb_audio_usbspeaker
     }
 
     *buffer = out;
-    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_MAX_CHANNELS)) {
+    if (MP_LIKELY(usb_audio_channel_count == USB_AUDIO_N_CHANNELS)) {
         *buffer_length = half;
     } else {
         *buffer_length = half >> 1;
diff --git a/shared-module/usb_audio/USBSpeaker.h b/shared-module/usb_audio/USBSpeaker.h
index 27007ad275d..0760676b53a 100644
--- a/shared-module/usb_audio/USBSpeaker.h
+++ b/shared-module/usb_audio/USBSpeaker.h
@@ -23,7 +23,7 @@
 #define USB_AUDIO_SPEAKER_FRAMES_PER_BUFFER (128)
 
 // Bytes per audio frame in the negotiated UAC2 format (stereo 16-bit).
-#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_BYTES_PER_SAMPLE * USB_AUDIO_MAX_CHANNELS)
+#define USB_AUDIO_SPEAKER_BYTES_PER_FRAME (USB_AUDIO_N_BYTES_PER_SAMPLE * USB_AUDIO_N_CHANNELS)
 
 // Full owned double-buffer: two halves of FRAMES_PER_BUFFER frames each. Matches
 // audiocore.RawSample's convention where base.max_buffer_length is the whole
diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index 516bcd53112..5840c861e7e 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -43,8 +43,8 @@ bool usb_audio_microphone_enabled;
 bool usb_audio_speaker_enabled;
 
 // Audio control state surfaced to the host. One extra entry for the master channel 0.
-static int8_t usb_audio_mute[USB_AUDIO_MAX_CHANNELS + 1];
-static int16_t usb_audio_volume[USB_AUDIO_MAX_CHANNELS + 1];
+static int8_t usb_audio_mute[USB_AUDIO_N_CHANNELS + 1];
+static int16_t usb_audio_volume[USB_AUDIO_N_CHANNELS + 1];
 
 bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count, bool microphone, bool speaker) {
     if (tud_connected()) {
@@ -53,7 +53,7 @@ bool shared_module_usb_audio_enable(mp_int_t sample_rate, mp_int_t channel_count
 
     // One scratch chunk (1 ms at the sample rate); we loop until the FIFO reaches
     // the setpoint.
-    usb_audio_mic_samples_len = sample_rate / 1000 * channel_count * USB_AUDIO_BYTES_PER_SAMPLE;
+    usb_audio_mic_samples_len = sample_rate / 1000 * channel_count * USB_AUDIO_N_BYTES_PER_SAMPLE;
     usb_audio_mic_samples = (int16_t *)m_malloc_without_collect(usb_audio_mic_samples_len);
     if (usb_audio_mic_samples == NULL) {
         m_malloc_fail(usb_audio_mic_samples_len);
@@ -155,7 +155,7 @@ void usb_audio_setup_singletons(void) {
     /* Clock Source Descriptor(4.7.2.1) */ \
     TUD_AUDIO20_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO20_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO20_CTRL_R << AUDIO20_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00), \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO20_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -165,7 +165,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the input terminal */ \
-    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO20_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -188,7 +188,7 @@ void usb_audio_setup_singletons(void) {
   /* Clock Source Descriptor(4.7.2.1) */ \
   TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
   /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
-  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
   /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
   TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
   /* Feature Unit Descriptor(4.7.2.8) */ \
@@ -200,7 +200,7 @@ void usb_audio_setup_singletons(void) {
   /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
   TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
   /* Class-Specific AS Interface Descriptor(4.9.2) */ \
-  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
   /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
   TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
   /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -229,14 +229,14 @@ void usb_audio_setup_singletons(void) {
     TUD_AUDIO20_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO20_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO20_CTRL_R << AUDIO20_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ 0x00, /*_stridx*/ 0x00), \
     /* --- Speaker chain (host -> board) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- USB streaming in from the host */ \
-    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO20_DESC_FEATURE_UNIT(/*_unitid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_stridx*/ 0x00, /*_ctrlch0master*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS), \
     /* Output Terminal Descriptor(4.7.2.5) -- desktop speaker */ \
     TUD_AUDIO20_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x00, /*_srcid*/ USB_AUDIO_HS_ENTITY_SPK_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
     /* --- Mic chain (board -> host) --- */ \
     /* Input Terminal Descriptor(4.7.2.4) -- generic microphone */ \
-    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ USB_AUDIO_HS_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
     /* Feature Unit Descriptor(4.7.2.8) */ \
     TUD_AUDIO20_DESC_FEATURE_UNIT(/*_unitid*/ USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_HS_ENTITY_MIC_INPUT_TERMINAL, /*_stridx*/ 0x00, /*_ctrlch0master*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS), \
     /* Output Terminal Descriptor(4.7.2.5) -- USB streaming out to the host */ \
@@ -247,7 +247,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one OUT endpoint */ \
     TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the speaker input terminal */ \
-    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_SPK_INPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO20_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -260,7 +260,7 @@ void usb_audio_setup_singletons(void) {
     /* Standard AS Interface Descriptor(4.9.1) -- alt 1, one IN endpoint */ \
     TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 2), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00), \
     /* Class-Specific AS Interface Descriptor(4.9.2) -- linked to the mic output terminal */ \
-    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_MAX_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
+    TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_HS_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00), \
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
     TUD_AUDIO20_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
@@ -319,7 +319,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
             USB_AUDIO_HEADSET_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
-                /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
+                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
                 /*_epout*/ ep_out,
                 /*_epin*/ ep_in | 0x80,
@@ -334,9 +334,9 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         // One IAD wrapping an AudioControl + two AudioStreaming interfaces, plus
         // two OUT and two IN endpoints.
         descriptor_counts->current_interface += 3;
-        descriptor_counts->num_out_endpoints += USB_AUDIO_MAX_CHANNELS;
-        descriptor_counts->num_in_endpoints += USB_AUDIO_MAX_CHANNELS;
-        descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS * 2;
+        descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS * 2;
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
 
@@ -353,7 +353,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
             USB_AUDIO_SPEAKER_DESCRIPTOR(
                 /*_itfnum*/ descriptor_counts->current_interface,
                 /*_stridx*/ *current_interface_string,
-                /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
+                /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
                 /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
                 /*_epout*/ iso_ep_num,
                 /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
@@ -363,8 +363,8 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two OUT endpoints.
         descriptor_counts->current_interface += 2;
         if (!forced_iso_ep) {
-            descriptor_counts->num_out_endpoints += USB_AUDIO_MAX_CHANNELS;
-            descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS;
+            descriptor_counts->num_out_endpoints += USB_AUDIO_N_CHANNELS;
+            descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
         }
 
         memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
@@ -381,7 +381,7 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
         USB_AUDIO_MIC_DESCRIPTOR(
             /*_itfnum*/ descriptor_counts->current_interface,
             /*_stridx*/ *current_interface_string,
-            /*_nBytesPerSample*/ USB_AUDIO_BYTES_PER_SAMPLE,
+            /*_nBytesPerSample*/ USB_AUDIO_N_BYTES_PER_SAMPLE,
             /*_nBitsUsedPerSample*/ USB_AUDIO_BITS_PER_SAMPLE,
             /*_epin*/ iso_ep_num | 0x80,
             /*_epsize*/ CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
@@ -391,8 +391,8 @@ size_t usb_audio_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *de
     // One IAD wrapping an AudioControl + an AudioStreaming interface, plus two IN endpoints.
     descriptor_counts->current_interface += 2;
     if (!forced_iso_ep) {
-        descriptor_counts->num_in_endpoints += USB_AUDIO_MAX_CHANNELS;
-        descriptor_counts->current_endpoint += USB_AUDIO_MAX_CHANNELS;
+        descriptor_counts->num_in_endpoints += USB_AUDIO_N_CHANNELS;
+        descriptor_counts->current_endpoint += USB_AUDIO_N_CHANNELS;
     }
 
     memcpy(descriptor_buf, usb_audio_descriptor, sizeof(usb_audio_descriptor));
@@ -544,7 +544,7 @@ bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Mute/volume state is shared across them.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
+        if (channelNum > USB_AUDIO_N_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
@@ -582,7 +582,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
         switch (ctrlSel) {
             case AUDIO20_TE_CTRL_CONNECTOR: {
                 audio20_desc_channel_cluster_t ret;
-                ret.bNrChannels = USB_AUDIO_MAX_CHANNELS;
+                ret.bNrChannels = USB_AUDIO_N_CHANNELS;
                 ret.bmChannelConfig = (audio20_channel_config_t)0;
                 ret.iChannelNames = 0;
                 return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &ret, sizeof(ret));
@@ -595,7 +595,7 @@ bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
     // Feature unit (mute/volume) for either the speaker or mic chain.
     if (entityID == USB_AUDIO_ENTITY_FEATURE_UNIT ||
         entityID == USB_AUDIO_HS_ENTITY_MIC_FEATURE_UNIT) {
-        if (channelNum > USB_AUDIO_MAX_CHANNELS) {
+        if (channelNum > USB_AUDIO_N_CHANNELS) {
             return false;
         }
         switch (ctrlSel) {
diff --git a/shared-module/usb_audio/usb_audio_descriptors.h b/shared-module/usb_audio/usb_audio_descriptors.h
index a1ec26b26ca..40691a17529 100644
--- a/shared-module/usb_audio/usb_audio_descriptors.h
+++ b/shared-module/usb_audio/usb_audio_descriptors.h
@@ -26,11 +26,11 @@ size_t usb_audio_descriptor_length(void);
 // The isochronous IN endpoint's wMaxPacketSize in the USB descriptor is computed
 // for this rate, so it is the highest rate usb_audio.enable() will accept.
 #define USB_AUDIO_MAX_SAMPLE_RATE (48000)
-#define USB_AUDIO_MAX_CHANNELS (2)
+#define USB_AUDIO_N_CHANNELS (2)
 
 // 16-bit signed LE PCM.
-#define USB_AUDIO_BYTES_PER_SAMPLE (2)
-#define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_BYTES_PER_SAMPLE * 8)
+#define USB_AUDIO_N_BYTES_PER_SAMPLE (2)
+#define USB_AUDIO_BITS_PER_SAMPLE (USB_AUDIO_N_BYTES_PER_SAMPLE * 8)
 
 // Endpoint number for the single isochronous audio data endpoint. Most device
 // controllers accept an ISO endpoint on any number, so the descriptor builder
diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
index 9421dd03e0d..ac63542b8e4 100644
--- a/supervisor/shared/usb/tusb_config.h
+++ b/supervisor/shared/usb/tusb_config.h
@@ -127,7 +127,7 @@ extern "C" {
 
 #define CFG_TUD_AUDIO_ENABLE_EP_IN                  1
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(TUD_OPT_HIGH_SPEED, USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX           TUD_AUDIO_EP_SIZE(TUD_OPT_HIGH_SPEED, USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
 // Deep software FIFO so the 1 ms refill keeps clear of the underrun floor.
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ        (16 * CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX)
 
@@ -137,7 +137,7 @@ extern "C" {
 // IN sizing above.
 #define CFG_TUD_AUDIO_ENABLE_EP_OUT                 1
 // wMaxPacketSize, sized for the highest supported sample rate.
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(TUD_OPT_HIGH_SPEED, USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_BYTES_PER_SAMPLE, USB_AUDIO_MAX_CHANNELS)
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TUD_AUDIO_EP_SIZE(TUD_OPT_HIGH_SPEED, USB_AUDIO_MAX_SAMPLE_RATE, USB_AUDIO_N_BYTES_PER_SAMPLE, USB_AUDIO_N_CHANNELS)
 // Deep software FIFO so the 1 ms drain keeps clear of the overrun ceiling.
 #define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ       (16 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX)
 #endif

From 6f29d4529540ccf74495648586bb2f3bbd6f1616 Mon Sep 17 00:00:00 2001
From: Cooper Dalrymple <dcooperdalrymple@gmail.com>
Date: Mon, 13 Jul 2026 11:34:33 -0500
Subject: [PATCH 11/11] Update stereo mic descriptor

---
 shared-module/usb_audio/__init__.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/shared-module/usb_audio/__init__.c b/shared-module/usb_audio/__init__.c
index 5840c861e7e..2a5948bb74f 100644
--- a/shared-module/usb_audio/__init__.c
+++ b/shared-module/usb_audio/__init__.c
@@ -174,39 +174,39 @@ void usb_audio_setup_singletons(void) {
     TUD_AUDIO20_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO20_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_lockdelayunit*/ AUDIO20_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
 
 // Hand-rolled UAC2 microphone (board -> host) descriptor WITHOUT an async
-// feedback endpoint. This mirrors TinyUSB's TUD_AUDIO_MIC_ONE_CH_DESCRIPTOR
+// feedback endpoint. This mirrors TinyUSB's TUD_AUDIO20_MIC_ONE_CH_DESCRIPTOR
 // (lib/tinyusb/src/device/usbd.h) but drops the trailing feedback endpoint, so
 // the streaming alt-setting declares a single IN endpoint (_nEPs = 0x00). Async
 // feedback for true clock matching is a later step.
 #define USB_AUDIO_MIC_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epin, _epsize) \
   /* Standard Interface Association Descriptor (IAD) */ \
-  TUD_AUDIO_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
+  TUD_AUDIO20_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00), \
   /* Standard AC Interface Descriptor(4.7.1) */ \
-  TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
+  TUD_AUDIO20_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx), \
   /* Class-Specific AC Interface Header Descriptor(4.7.2) */ \
-  TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_MICROPHONE, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN + TUD_AUDIO_DESC_INPUT_TERM_LEN + TUD_AUDIO_DESC_OUTPUT_TERM_LEN + TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
+  TUD_AUDIO20_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO20_FUNC_MICROPHONE, /*_totallen*/ TUD_AUDIO20_DESC_CLK_SRC_LEN + TUD_AUDIO20_DESC_INPUT_TERM_LEN + TUD_AUDIO20_DESC_OUTPUT_TERM_LEN + TUD_AUDIO20_DESC_FEATURE_UNIT_LEN(2), /*_ctrl*/ AUDIO20_CS_AS_INTERFACE_CTRL_LATENCY_POS), \
   /* Clock Source Descriptor(4.7.2.1) */ \
-  TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO_CTRL_R << AUDIO_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
+  TUD_AUDIO20_DESC_CLK_SRC(/*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_attr*/ AUDIO20_CLOCK_SOURCE_ATT_INT_FIX_CLK, /*_ctrl*/ (AUDIO20_CTRL_R << AUDIO20_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL,  /*_stridx*/ 0x00), \
   /* Input Terminal Descriptor(4.7.2.4) -- microphone */ \
-  TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
+  TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_nchannelslogical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS, /*_stridx*/ 0x00), \
   /* Output Terminal Descriptor(4.7.2.5) -- USB streaming */ \
-  TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
+  TUD_AUDIO20_DESC_OUTPUT_TERM(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_srcid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_clkid*/ USB_AUDIO_ENTITY_CLOCK_SOURCE, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00), \
   /* Feature Unit Descriptor(4.7.2.8) */ \
-  TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_ctrlch0master*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO_CTRL_RW << AUDIO_FEATURE_UNIT_CTRL_VOLUME_POS, /*_stridx*/ 0x00), \
+  TUD_AUDIO20_DESC_FEATURE_UNIT(/*_unitid*/ USB_AUDIO_ENTITY_FEATURE_UNIT, /*_srcid*/ USB_AUDIO_ENTITY_INPUT_TERMINAL, /*_stridx*/ 0x00, /*_ctrlch0master*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS), \
   /* Standard AS Interface Descriptor(4.9.1) */ \
   /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */ \
-  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
+  TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
   /* Standard AS Interface Descriptor(4.9.1) */ \
   /* Interface 1, Alternate 1 - alternate interface for data streaming */ \
-  TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
+  TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x00),\
   /* Class-Specific AS Interface Descriptor(4.9.2) */ \
-  TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ USB_AUDIO_ENTITY_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ USB_AUDIO_N_CHANNELS, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
   /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */ \
-  TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
+  TUD_AUDIO20_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample), \
   /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */ \
-  TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
+  TUD_AUDIO20_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epsize, /*_interval*/ 0x01), \
   /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */ \
-  TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
+  TUD_AUDIO20_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO20_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_lockdelayunit*/ AUDIO20_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)
 
 // Hand-rolled UAC2 headset (microphone + speaker both enabled): one audio function
 // presenting both a speaker (host -> board OUT) and a microphone (board -> host